New Legislation from:http://www.tirereview.com/?type=art&id=5278&Finally, you should be aware of some new legislation regarding the installation of aftermarket wheels and non-OE tires on a new vehicle that hasn’t been titled yet. The new rule, Federal Motor Vehicle Safety Standard #110, which took effect Sept. 1, 2005, states that if you “alter” a new vehicle by installing different tires or wheels, you must place a new tire inflation and load capacity placard over the original to indicate the new front/rear/spare air pressures to the buyer.
SEMA has compiled recommendations to help you avoid any problems that may arise due to differing interpretations of the ruling. You can order the placards from various label makers.
If you are interested in getting this information, feel free to contact me, and I will direct you to several companies compiled by NHTSA. This standard applies to changes in the vehicle’s weight capacity, as well. If you install products that add weight to the vehicle, you will need to indicate the new weight capacity of the vehicle, which will be the manufacturer’s listed weight less the amount you added. NHTSA does allow for a 0.5% deviation of the gross vehicle weight rating without replacing the placard, but this may change in the coming months.
This law should be made to apply to owners and shops after vehicle is sold and when ever a used car is traded/sold
Add just 20 pounds to a 3999 pound vehicle and you are required to design and change the placard............after market wheels or chroming oem wheels, or audio system [sub woofer]...............new car dealers beware!
New Legislation
-
elwesso
- Posts: 30810
- Joined: Sun Feb 23, 2003 4:52 pm
- Car: 94 Infiniti Q45t 5 spd
2007 BMW M Coupe
2007 Infiniti G35 S 6MT - Location: Indiana
- Contact:
Re: New Legislation (Q45tech)
COPY OF MY POST FROM THE M45 FORUM
That was a GREAT read tech... Thanks a bunch...
Maybe you could clarify something. On my tires it says MAX LOAD 1521@51 PSI on the sidewall. however in the article, it says that the MAX LOAD is calculated at the factory PSI, in these cases, at 35PSI cold... However, if you look at this picture, you will see that it sorta lists them as 2 different things.
So I ask, what pressure is the load index calculated from? Is it at the MAX pressure? Is that why some tire companies offer extra load rating tires by simply increasing their max inflation.. Meaning they can make the tire pretty much the same but offer it in a 95 or a 99 load rating, with a 44 or 51 psi max inflation, respectively....
That was a GREAT read tech... Thanks a bunch...
Maybe you could clarify something. On my tires it says MAX LOAD 1521@51 PSI on the sidewall. however in the article, it says that the MAX LOAD is calculated at the factory PSI, in these cases, at 35PSI cold... However, if you look at this picture, you will see that it sorta lists them as 2 different things.
So I ask, what pressure is the load index calculated from? Is it at the MAX pressure? Is that why some tire companies offer extra load rating tires by simply increasing their max inflation.. Meaning they can make the tire pretty much the same but offer it in a 95 or a 99 load rating, with a 44 or 51 psi max inflation, respectively....
-
Q45tech
- Moderator
- Posts: 14296
- Joined: Tue Apr 30, 2002 3:19 am
- Car: 1990 Q45 342,400 miles 22 years ownership with original engine
1995 G20t 5 speed 334,000 miles 16" 2002 wheels - 205/50/16 Sr20ve vvl
Re: New Legislation (Q45tech)
Obviously the Federal Government knows how little extra safety reserve is being added to modern cars. They have taken note of all the heavy weight mods ...........tires/wheels/sound system
Add a front strut tower brace and rear sway bars and a subwoofer and you are over the limit even on a Q.
You will have to weigh all your passengers and luggage.........just like the airlines SHOULD to determine your fuel surcharge.
Add a front strut tower brace and rear sway bars and a subwoofer and you are over the limit even on a Q.
You will have to weigh all your passengers and luggage.........just like the airlines SHOULD to determine your fuel surcharge.
-
Q45tech
- Moderator
- Posts: 14296
- Joined: Tue Apr 30, 2002 3:19 am
- Car: 1990 Q45 342,400 miles 22 years ownership with original engine
1995 G20t 5 speed 334,000 miles 16" 2002 wheels - 205/50/16 Sr20ve vvl
Re: New Legislation (Q45tech)
The new 51 psi tires have thrown a monkey wrench into the old methods.
For years all tires were 35 psi max and that was where they were measured............when 44 psi tires were first made by Michelin the others got upset that Michelin could do it since they had enough extra reserve strength via using more expensive materials...........they lobbied the testing orgs to still use 35 psi. So 44 psi tires are still tested at 35 psi...........doesn't mean it's right or safe or anything just how it's done.
51 psi tires are a really new animal without standards as to where they should be tested other than 51 psi.
Vehicle manufacturers test at the placard psi on a machine and test track and the street..............but alignment is kept perfect as is inflation.
It's not that the tire will immediately fail if over loaded or under inflated by a small amount. IT IS THE USED TIRE THAT IS THE PROBLEM THE HALF WORN TIRE.
I had these discussion with Michelin via extensive emails which cannot be published...........the jist was to use a static weight on the tire of ABSOLUTELY no more than 80% of the max rating and to inflated to 80% of the max pressure 41 PSI for a 51 PSI MAX tire if vigorous driving was the norm and safety a prime concern ALONG WITH REASONABLE LIFE.
NO COMPANY WILL SAY THAT THE PLACARDS ARE WRONG.
The Q has 1180 static on 1521 tires that is 77.6% on a standard and 80.9% on an Active............the Placard says 35 psi cold for a 44psi 95V MICHELIN TIRE with performance driving.
The question is HOW MUCH STRONGER are MICHELIN tires [in their strongest highest performance model] than other brands and are owners using the most expensive top of the line model in another brand?
For years all tires were 35 psi max and that was where they were measured............when 44 psi tires were first made by Michelin the others got upset that Michelin could do it since they had enough extra reserve strength via using more expensive materials...........they lobbied the testing orgs to still use 35 psi. So 44 psi tires are still tested at 35 psi...........doesn't mean it's right or safe or anything just how it's done.
51 psi tires are a really new animal without standards as to where they should be tested other than 51 psi.
Vehicle manufacturers test at the placard psi on a machine and test track and the street..............but alignment is kept perfect as is inflation.
It's not that the tire will immediately fail if over loaded or under inflated by a small amount. IT IS THE USED TIRE THAT IS THE PROBLEM THE HALF WORN TIRE.
I had these discussion with Michelin via extensive emails which cannot be published...........the jist was to use a static weight on the tire of ABSOLUTELY no more than 80% of the max rating and to inflated to 80% of the max pressure 41 PSI for a 51 PSI MAX tire if vigorous driving was the norm and safety a prime concern ALONG WITH REASONABLE LIFE.
NO COMPANY WILL SAY THAT THE PLACARDS ARE WRONG.
The Q has 1180 static on 1521 tires that is 77.6% on a standard and 80.9% on an Active............the Placard says 35 psi cold for a 44psi 95V MICHELIN TIRE with performance driving.
The question is HOW MUCH STRONGER are MICHELIN tires [in their strongest highest performance model] than other brands and are owners using the most expensive top of the line model in another brand?
Re: New Legislation (Q45tech)
That's the $64k question.Q45tech wrote:... The question is HOW MUCH STRONGER are MICHELIN tires [in their strongest highest performance model] than other brands and are owners using the most expensive top of the line model in another brand?
I'd take a 94/95 load rated Mich/Bridgestone tire over a 96 or even 98 load rated "cheapo".
-
squeefoo
- Posts: 1053
- Joined: Tue Jul 22, 2003 5:10 pm
- Car: 1990 Infiniti Q45
1994 Nissan Maxima SE
1999 Infiniti I30
2003 Nissan Maxima Titanium
2006 Nissan Xterra Off Road
2012 Infiniti G37x S
Re: New Legislation (Q45tech)
Thank you Uncle Shem for more intrusion.
Which part of my life can I live?
If you think we're free... think again.
Which part of the UCC do I fall under next ?????
Which part of my life can I live?
If you think we're free... think again.
Which part of the UCC do I fall under next ?????
-
elwesso
- Posts: 30810
- Joined: Sun Feb 23, 2003 4:52 pm
- Car: 94 Infiniti Q45t 5 spd
2007 BMW M Coupe
2007 Infiniti G35 S 6MT - Location: Indiana
- Contact:
Re: New Legislation (Q45tech)
Tech, I am posting this as sort of a thinking out loud sort of thing, please critique as you see fit. I'm not trying to preach or say I'm right, I want to find out if I'm right
Ok.. so lets assume 4136 (94 Q45t), 3850 (CURB WEIGHT, NOT AS TESTED), 4020 (for another 90 Q, 1989 C/D), and 4160 for anothet 1990 Q ..... weight distribution is roughly 58/42 (some have said 57/43). 95 Q had a 4240 test weight.
IMPORTANT to realize that NO Q45 actual test weight was below 4000 LB... Curb weight certainly was, but of course the tested weight may or may not have had drivers in it. So from those numbers lets say (throwing out the lowest one), lets work with the heaviest one listed, 4240lbs.... I think its probbaly fairer to use these heavier weights which likely include driver...
So extrapolating this data, youd be left with 1230lb up front per (2459/2)... So according to my calculations thatd mean we'd want at least 1328lb load rating up front (1230 x 1.08=1328).. Which means of course the closest load rating to that is 91 (1356). With 91 load tire youd be over the minimum by 2%... Still within the safe margin according to what your saying...
http://www.tirecradle.com/tire...tings:
For a michelin tire or equal quality (if such a beast exists) I would think that a 91 load rating would technically be safe, however you might want to go for a 93 load rating to be 8% over the min.
however stock pressure of 28PSI is only 64% of the 44psi (i assume stock tires were a 44 psi). Since they inflated them less, that would the load rating seem less... Even though it was a 95 load tire, it didnt seem like it because they were inflated at 80% of the load tested [35PSI]. SO if they inflated the tires to 35 PSI, a 93 load rating may have been sufficient from the factory.... ALSO clearly you could get away with a lower load rating on the rear of the car if you wanted to, but if you run the same size tire or a wider tire in the rear this isnt a big deal.
One thing its important to realize that I am not advocating using less than 95 load rating, but if what your saying is true, a 93 load rating on a good tire should be fine.
Ok.. so lets assume 4136 (94 Q45t), 3850 (CURB WEIGHT, NOT AS TESTED), 4020 (for another 90 Q, 1989 C/D), and 4160 for anothet 1990 Q ..... weight distribution is roughly 58/42 (some have said 57/43). 95 Q had a 4240 test weight.
IMPORTANT to realize that NO Q45 actual test weight was below 4000 LB... Curb weight certainly was, but of course the tested weight may or may not have had drivers in it. So from those numbers lets say (throwing out the lowest one), lets work with the heaviest one listed, 4240lbs.... I think its probbaly fairer to use these heavier weights which likely include driver...
So extrapolating this data, youd be left with 1230lb up front per (2459/2)... So according to my calculations thatd mean we'd want at least 1328lb load rating up front (1230 x 1.08=1328).. Which means of course the closest load rating to that is 91 (1356). With 91 load tire youd be over the minimum by 2%... Still within the safe margin according to what your saying...
http://www.tirecradle.com/tire...tings:
For a michelin tire or equal quality (if such a beast exists) I would think that a 91 load rating would technically be safe, however you might want to go for a 93 load rating to be 8% over the min.
however stock pressure of 28PSI is only 64% of the 44psi (i assume stock tires were a 44 psi). Since they inflated them less, that would the load rating seem less... Even though it was a 95 load tire, it didnt seem like it because they were inflated at 80% of the load tested [35PSI]. SO if they inflated the tires to 35 PSI, a 93 load rating may have been sufficient from the factory.... ALSO clearly you could get away with a lower load rating on the rear of the car if you wanted to, but if you run the same size tire or a wider tire in the rear this isnt a big deal.
One thing its important to realize that I am not advocating using less than 95 load rating, but if what your saying is true, a 93 load rating on a good tire should be fine.
-
Q45tech
- Moderator
- Posts: 14296
- Joined: Tue Apr 30, 2002 3:19 am
- Car: 1990 Q45 342,400 miles 22 years ownership with original engine
1995 G20t 5 speed 334,000 miles 16" 2002 wheels - 205/50/16 Sr20ve vvl
Re: New Legislation (elwesso)
They usually discount braking weight on front [because the braking is so quick ~~ 3-4 seconds*] which is at best 25" blended CG/113.2" wheel base or 22% of rear sprung weight added to front ~~ 400-425 pounds ...............this can be checked by the amount of front drive [146 pound inch springs x 2 = 1.369"................we know it is more than this so the blended CG must be greater...........reverse engineering says something like ~500-550 pounds is transfered in a panic stop with ABS activation.
Divide the 500 by 2 adds 250-275 pounds to each tires static weight load.
Consider a 0.75G turn with a 22 front CG and 61" track 1100 pounds x 22/61=0.36 x 0.75= 0.270 x 1100= ~~300 pounds added to static weight on opposite tire. Roughly a 2" body roll. YET we know a Q can roll 7 degrees roughly 2.8"...............why because the springs are not mounted at the center of the tire/wheel and thus the 146 pound inch springs in series with the tire at 1000-1500 lb/in and all the rubber top and bottom bushings ACT like 107 pounds of roll stiffness.
With 15% stiffer Eibach's and the same tires rubber bushings so front acts like 123 pounds per inch and roll is 2.4" vs 2.8" [stiffen front bar with washers reduces roll dramatically] but doesn't change the tire loading much.
It is much more like that these handling forces will be seen more frequently than panic stopping from 80 mph.
If I am correct that 1180 pounds is the typical front tire static load then the tire sees 1480 pounds..........pretty close to the 1521 pounds a 95V is rated for................97.3% of full max load.
Think shape of contact patch under turning load and the two things that resist deformation: PSI [sidewall] and tire strength [load index]...........why racers measure the tire temperature across the face and try to equalize to maintain the optimum tread shape that creates an even friction across the tire. High static negative camber forces more weight on inside thus higher friction thus faster inside wear. But we do this to help square the tire under a turning load.
The only way you know for sure is to drive the tire around a glass roadway and take pictures of the tread or measure the tire face temperature.
Remember I only weight 165 pounds and that is 15 pounds over the driver design weight. The 1990 and 1991 launch books say the standard Q weights 3957 pounds, 3993 touring, 4000 with tcs, and 4156 active. I expect these are empty gas and sans driver.........the car as shipped on the boat with maybe a gallon in tank.
Why I alwas add 300 pounds ~~ 4257 plus 5 pounds for rear sway bar and 5 for strut tower brace ~~4267 pounds says roughy 1150-1180 on each front tire.
I have an interesting experiment underway 235/60/15 on front and 215/65/15 on rear same Michelin H4 all with the same 1/2 worn tread depth all around on 94 wheels.............I can definitely feel the weaker tires on the rear.
1620 front vs 1521 rear using same inflation 35 psi cold........experimenting with 37 rear and 39 rear.
Not my fault that Americans weigh more than Japanese.
Divide the 500 by 2 adds 250-275 pounds to each tires static weight load.
Consider a 0.75G turn with a 22 front CG and 61" track 1100 pounds x 22/61=0.36 x 0.75= 0.270 x 1100= ~~300 pounds added to static weight on opposite tire. Roughly a 2" body roll. YET we know a Q can roll 7 degrees roughly 2.8"...............why because the springs are not mounted at the center of the tire/wheel and thus the 146 pound inch springs in series with the tire at 1000-1500 lb/in and all the rubber top and bottom bushings ACT like 107 pounds of roll stiffness.
With 15% stiffer Eibach's and the same tires rubber bushings so front acts like 123 pounds per inch and roll is 2.4" vs 2.8" [stiffen front bar with washers reduces roll dramatically] but doesn't change the tire loading much.
It is much more like that these handling forces will be seen more frequently than panic stopping from 80 mph.
If I am correct that 1180 pounds is the typical front tire static load then the tire sees 1480 pounds..........pretty close to the 1521 pounds a 95V is rated for................97.3% of full max load.
Think shape of contact patch under turning load and the two things that resist deformation: PSI [sidewall] and tire strength [load index]...........why racers measure the tire temperature across the face and try to equalize to maintain the optimum tread shape that creates an even friction across the tire. High static negative camber forces more weight on inside thus higher friction thus faster inside wear. But we do this to help square the tire under a turning load.
The only way you know for sure is to drive the tire around a glass roadway and take pictures of the tread or measure the tire face temperature.
Remember I only weight 165 pounds and that is 15 pounds over the driver design weight. The 1990 and 1991 launch books say the standard Q weights 3957 pounds, 3993 touring, 4000 with tcs, and 4156 active. I expect these are empty gas and sans driver.........the car as shipped on the boat with maybe a gallon in tank.
Why I alwas add 300 pounds ~~ 4257 plus 5 pounds for rear sway bar and 5 for strut tower brace ~~4267 pounds says roughy 1150-1180 on each front tire.
I have an interesting experiment underway 235/60/15 on front and 215/65/15 on rear same Michelin H4 all with the same 1/2 worn tread depth all around on 94 wheels.............I can definitely feel the weaker tires on the rear.
1620 front vs 1521 rear using same inflation 35 psi cold........experimenting with 37 rear and 39 rear.
Not my fault that Americans weigh more than Japanese.
-
elwesso
- Posts: 30810
- Joined: Sun Feb 23, 2003 4:52 pm
- Car: 94 Infiniti Q45t 5 spd
2007 BMW M Coupe
2007 Infiniti G35 S 6MT - Location: Indiana
- Contact:
Re: New Legislation (Q45tech)
Alright I think I am following you. Basically what we are doing is assuming a .75G corner and then adding that static weight to opposite (load bearing) tire... I failed to take into consideration cornering load...
I think where I am most confused is what CG means. I assume it means center of gravity however I am simply not sure. Your math would likely make much more sense if this were clarified. I hope I am not stupifying the situation too much .
However, I want to know how you come up with the 1180 as the static number.. If you do this, your assuming a 2360 front end, thus making the rear 1708, thus making the car 4,068 (which MAY or MAY NOT include driver). Gas probably would not matter in this case since it would only REDUCE relative weight in the front). Might work for a 90-92 but as we all know a HICAS and active Q could very likely reach the higher number I figured... IN WHICH CASE would mean youd need a (1328+~300=1628) 98 [1653#] on one of those. however a Q45t's weight is pretty much in just the rear of the car [hicas rack], but on an active Q its spread out probably more towards the front (multivalve unit, more accumulators, fluid res, etc)..... May seem like overkill however you cannot be too safe!
I dont want to distract the main point from this though. Its POSSIBLE to say that heavier Q (94 active being the worst) 95 load is not sufficient. ALSO, as you increase the stickyness of the tires, its very possible you can turn higher Gs (would it be much higher than .75G, probably not), thus necessitating a slightly higher load rating tire!! Some cheap tires may not be capable of creating a .75G turn on the Q, especially with no rear sway bar! 94 Q45t pulled a .77G (july 1993 car and driver)
Notice that G35 use 91 load rated tires (225-45-18 91W) and it has a 54/46 weight distribution (5AT coupe). Curb weight is 3369lbs.. Sort of comparing apples and oranges since our Q weight is more real-world, still even assuming it weighs 3500 lbs, its still only 945lbs per tire front.. VERY much over rated. I just thought I would point that out. goes without saying that the wheel and tire [obviously tires arent] combo may not be completely suitable for use on the Q, but comparing the OEM G35 wheels to most aftermarket, OEM would be much stronger and lighter and ultimately win.
itd be interesting to see what moving the battery to the trunk does for the weight distribution in the real world. Could it possibly alleviate some of the excess weight in the front, making the front tires job a little easier?
I think where I am most confused is what CG means. I assume it means center of gravity however I am simply not sure. Your math would likely make much more sense if this were clarified. I hope I am not stupifying the situation too much .
However, I want to know how you come up with the 1180 as the static number.. If you do this, your assuming a 2360 front end, thus making the rear 1708, thus making the car 4,068 (which MAY or MAY NOT include driver). Gas probably would not matter in this case since it would only REDUCE relative weight in the front). Might work for a 90-92 but as we all know a HICAS and active Q could very likely reach the higher number I figured... IN WHICH CASE would mean youd need a (1328+~300=1628) 98 [1653#] on one of those. however a Q45t's weight is pretty much in just the rear of the car [hicas rack], but on an active Q its spread out probably more towards the front (multivalve unit, more accumulators, fluid res, etc)..... May seem like overkill however you cannot be too safe!
I dont want to distract the main point from this though. Its POSSIBLE to say that heavier Q (94 active being the worst) 95 load is not sufficient. ALSO, as you increase the stickyness of the tires, its very possible you can turn higher Gs (would it be much higher than .75G, probably not), thus necessitating a slightly higher load rating tire!! Some cheap tires may not be capable of creating a .75G turn on the Q, especially with no rear sway bar! 94 Q45t pulled a .77G (july 1993 car and driver)
Notice that G35 use 91 load rated tires (225-45-18 91W) and it has a 54/46 weight distribution (5AT coupe). Curb weight is 3369lbs.. Sort of comparing apples and oranges since our Q weight is more real-world, still even assuming it weighs 3500 lbs, its still only 945lbs per tire front.. VERY much over rated. I just thought I would point that out. goes without saying that the wheel and tire [obviously tires arent] combo may not be completely suitable for use on the Q, but comparing the OEM G35 wheels to most aftermarket, OEM would be much stronger and lighter and ultimately win.
itd be interesting to see what moving the battery to the trunk does for the weight distribution in the real world. Could it possibly alleviate some of the excess weight in the front, making the front tires job a little easier?
-
Q45tech
- Moderator
- Posts: 14296
- Joined: Tue Apr 30, 2002 3:19 am
- Car: 1990 Q45 342,400 miles 22 years ownership with original engine
1995 G20t 5 speed 334,000 miles 16" 2002 wheels - 205/50/16 Sr20ve vvl
Re: New Legislation (Q45tech)
a 93 load rating on a good tire should be fine
HOWEVER IT IS ILLEGAL [before titling] AND LEGALLY NEGLIGENT to install a weaker tire than that which came on the car brand new.
The real thing you are missing is when Nissan tested the Sport XGTV how much stronger was it than the minimal 95V rating........we know it was stronger because other tires with 95V ratings change balance and fail we see this everyday with current 95 load rated 44 and 51 psi tires.
The load rating is primarily an internal air volume factor as tires went from 25>44>51 less and less of the rating came from sidewall without inflation.
If I was using any other tire than Michelin I would go higher in the load rating tahn 95V to make sure what I got would be suitable.
Why for the last 10 years I've used 235/60/15 [a 98 load index] even with a Michelin tire because an H rated tire has less reserve than a V rated tire.
You get to drive your own car so you get to decide what is safe and what is not.....................no whinning allowed if you ever have a flat or a blow out or they don't last as long as you want or your car cannot exceed 0.7 G or stop better than 140 feet from 60 in the dry. Or they feather or wear weirdly.
HOWEVER IT IS ILLEGAL [before titling] AND LEGALLY NEGLIGENT to install a weaker tire than that which came on the car brand new.
The real thing you are missing is when Nissan tested the Sport XGTV how much stronger was it than the minimal 95V rating........we know it was stronger because other tires with 95V ratings change balance and fail we see this everyday with current 95 load rated 44 and 51 psi tires.
The load rating is primarily an internal air volume factor as tires went from 25>44>51 less and less of the rating came from sidewall without inflation.
If I was using any other tire than Michelin I would go higher in the load rating tahn 95V to make sure what I got would be suitable.
Why for the last 10 years I've used 235/60/15 [a 98 load index] even with a Michelin tire because an H rated tire has less reserve than a V rated tire.
You get to drive your own car so you get to decide what is safe and what is not.....................no whinning allowed if you ever have a flat or a blow out or they don't last as long as you want or your car cannot exceed 0.7 G or stop better than 140 feet from 60 in the dry. Or they feather or wear weirdly.
-
maxnix
- Posts: 22627
- Joined: Mon Jul 22, 2002 8:11 pm
- Car: 1995 Infiniti Q45
1995 Infiniti Q45t
2000 Infiniti Q45
Re: New Legislation (elwesso)
1.) Realative schmealative. The actual weight on the front end will increase with increasing fuel load.elwesso wrote:1.) Gas probably would not matter in this case since it would only REDUCE relative weight in the front).
2.) Notice that G35 use 91 load rated tires (225-45-18 91W) and it has a 54/46 weight distribution (5AT coupe). Curb weight is 3369lbs.. ?
2.) The new V35 (will they still be that chassis designation?) Sport model sedans will run 245/45-18. I doubt they will be much heavier than the current models.
Modified by maxnix at 9:30 PM 5/2/2006
-
elwesso
- Posts: 30810
- Joined: Sun Feb 23, 2003 4:52 pm
- Car: 94 Infiniti Q45t 5 spd
2007 BMW M Coupe
2007 Infiniti G35 S 6MT - Location: Indiana
- Contact:
Re: New Legislation (Q45tech)
I am certainly not saying that running a 93 load rating tire is SAFE, I was just saying this in relation to your post on the data that you gave to me. I am certainly not condoning this.. I guess my main scheme in doing all this was to get YOU to post some great information. I just like picking your brain! I think you are misunderstanding my point in that (which may have not been really clear) that 95 may not even be enough for a Q45a and such.
I understand that the Michelin tire used on the early Q may have acted like a 96-97-98 load rated tire by AVERAGE quality standards. I wish there were some way of knowing ABSOLUETLY this kind of stuff rather than just having to buy michelin to get quality. Oh well!
Brian, i see nothing where they are using 245-45-18 on the FRONT of the G35 COUPE which is what I was comparing. UNless of course your tlaking about the 2007 G35 coupe!
G35 Coupe 6-spoke, 17 x 7.5-inch aluminum-alloy wheels with 225/50R17 (front), 235/50R17 (rear) V-rated all-season performance tires
Performance Tire and Wheel Package 7-spoke, 18 x 8.0-inch aluminum-alloy wheels with 225/45R18 (front), 245/45R18 (rear) W-rated summer performance tires
Sport-tuned Suspension Package 5-spoke, 19 x 8.0-inch (front), 19 x 8.5-inch (rear) forged aluminum-alloy wheels with 225/40R19 (front), 245/40R19 (rear) Y-rated summer performance tires
You are correct about the G35 SEDAN with SPORT TUNED SUSPENSION using 245-45-18 all around.
I understand that the Michelin tire used on the early Q may have acted like a 96-97-98 load rated tire by AVERAGE quality standards. I wish there were some way of knowing ABSOLUETLY this kind of stuff rather than just having to buy michelin to get quality. Oh well!
Brian, i see nothing where they are using 245-45-18 on the FRONT of the G35 COUPE which is what I was comparing. UNless of course your tlaking about the 2007 G35 coupe!
G35 Coupe 6-spoke, 17 x 7.5-inch aluminum-alloy wheels with 225/50R17 (front), 235/50R17 (rear) V-rated all-season performance tires
Performance Tire and Wheel Package 7-spoke, 18 x 8.0-inch aluminum-alloy wheels with 225/45R18 (front), 245/45R18 (rear) W-rated summer performance tires
Sport-tuned Suspension Package 5-spoke, 19 x 8.0-inch (front), 19 x 8.5-inch (rear) forged aluminum-alloy wheels with 225/40R19 (front), 245/40R19 (rear) Y-rated summer performance tires
You are correct about the G35 SEDAN with SPORT TUNED SUSPENSION using 245-45-18 all around.
-
szh
- Posts: 15932
- Joined: Tue Jul 23, 2002 12:54 pm
- Car: 2018 Tesla Model 3.
Unfortunately, no longer a Nissan or Infiniti, but continuing here at NICO! - Location: San Jose, CA
Re: New Legislation (elwesso)
Here is my response there:elwesso wrote:COPY OF MY POST FROM THE M45 FORUM
Hi, Wes.
Per the Tire and Rubber Association ("TRA") Handbook, load index is generally stated at 35psi for P-metric (Passenger) Standard Load ("SL") tires. This was an old standard developed for 44psi max pressure tires, and has not been updated, AFAIK, for newer 51psi max pressure tires.
So, for all intents and purposes, a SL tire with 95 load index still means "1521 lbs at 35psi" (for most tires, although it can be lower - at 1499 and 1510 lbs - for a few tire sizes), with appropriate derating below that pressure.
An Extended or Extra Load ("XL") tire is measured at 41psi by the way, so you have to be very careful to recognize that an XL tire with a load index of 95 means "1521 lbs at 41psi". This is quite different from an SL tire! Hence, that article has a very good point about how to recognize the actual load capacity of the tire.
I have tire tables that demonstrate this information for a given tire size, although it is a bit out of date now (I have not yet sprung for the latest Handbook from the TRA - I should do that!).
Z
-
szh
- Posts: 15932
- Joined: Tue Jul 23, 2002 12:54 pm
- Car: 2018 Tesla Model 3.
Unfortunately, no longer a Nissan or Infiniti, but continuing here at NICO! - Location: San Jose, CA
Re: New Legislation (Rex)
Very true. But, good "non-cheapo" tires should be just fine, particularly with higher load index values. For example, I use a 100W Goodyear Eagle F1 GS-D3 on my current M45. Gives me that extra feeling of safety, I think.Rex wrote:I'd take a 94/95 load rated Mich/Bridgestone tire over a 96 or even 98 load rated "cheapo".
I run my tires at 36 psi to get to that load index rating. Yeah, I could run it at 41psi (80% of the max 51psi), but the ride would be quite a bit harsher ... and not needed, IMHO, since it is a 100 load index tire.
Z
-
elwesso
- Posts: 30810
- Joined: Sun Feb 23, 2003 4:52 pm
- Car: 94 Infiniti Q45t 5 spd
2007 BMW M Coupe
2007 Infiniti G35 S 6MT - Location: Indiana
- Contact:
Re: New Legislation (szhosain)
Thanks for bringing that over here!szhosain wrote:Here is my response there:
Hi, Wes.
Per the Tire and Rubber Association ("TRA") Handbook, load index is generally stated at 35psi for P-metric (Passenger) Standard Load ("SL") tires. This was an old standard developed for 44psi max pressure tires, and has not been updated, AFAIK, for newer 51psi max pressure tires.
So, for all intents and purposes, a SL tire with 95 load index still means "1521 lbs at 35psi" (for most tires, although it can be lower - at 1499 and 1510 lbs - for a few tire sizes), with appropriate derating below that pressure.
An Extended or Extra Load ("XL") tire is measured at 41psi by the way, so you have to be very careful to recognize that an XL tire with a load index of 95 means "1521 lbs at 41psi". This is quite different from an SL tire! Hence, that article has a very good point about how to recognize the actual load capacity of the tire.
I have tire tables that demonstrate this information for a given tire size, although it is a bit out of date now (I have not yet sprung for the latest Handbook from the TRA - I should do that!).
Z
-
Q45tech
- Moderator
- Posts: 14296
- Joined: Tue Apr 30, 2002 3:19 am
- Car: 1990 Q45 342,400 miles 22 years ownership with original engine
1995 G20t 5 speed 334,000 miles 16" 2002 wheels - 205/50/16 Sr20ve vvl
Re: New Legislation (elwesso)
What gets me is people using wider lower than oem load rated tires, on bigger diameter wheels with a longer wearing tread compound -- thinking they are improving handling.
They may have stiffer side walls which when in series with the vehicle springs make the roll stiffness higher but the tread friction [or the lack thereof] hurts more than the gain.
Measure the unloaded radius, then lower the car on the ground the new LOADED RADIUS shows you the side wall stiffness at the current inflation pressure. ................ lose 0.7 " with 1150 pounds of weight on the tire and you have a side wall stiffness of 1150/0.7= 1643 pounds per inch.
As the psi goes up from heating, the sidewall stiffness goes up.
Have some fun:http://www.myphysicslab.com/dbl_spring1.html
http://othello.mech.northweste....html
They may have stiffer side walls which when in series with the vehicle springs make the roll stiffness higher but the tread friction [or the lack thereof] hurts more than the gain.
Measure the unloaded radius, then lower the car on the ground the new LOADED RADIUS shows you the side wall stiffness at the current inflation pressure. ................ lose 0.7 " with 1150 pounds of weight on the tire and you have a side wall stiffness of 1150/0.7= 1643 pounds per inch.
As the psi goes up from heating, the sidewall stiffness goes up.
Have some fun:http://www.myphysicslab.com/dbl_spring1.html
http://othello.mech.northweste....html
-
Q45tech
- Moderator
- Posts: 14296
- Joined: Tue Apr 30, 2002 3:19 am
- Car: 1990 Q45 342,400 miles 22 years ownership with original engine
1995 G20t 5 speed 334,000 miles 16" 2002 wheels - 205/50/16 Sr20ve vvl
Re: New Legislation (Q45tech)
The top spring seat is a spring, the classical spring is a spring, the wheel is a spring and the tire is a spring............4 springs in series........do the calculations and you will find that a Q45 front spring of 146 lb/in is really 115-125 lb/in at the road surface depending on tire and it's inflation............by the way the road is a spring and under the tire patch it moves minutely say 113-123 lb/in.Installing lowering springs that are exactly 15% stiffer does not mean that the roll stiffness increases exactly 15%.........more like 13%.
Way off topic but all has a bearing on tires and modifying oem tires.
Way off topic but all has a bearing on tires and modifying oem tires.