TIRE QUESTION - SAFETY

[Larz]

I will need tires very soon. I have an M35-RWD (2007) with the factory 18" 8-spoke chrome wheels. I am 90% certain they are 8in wide but haven't been able to verify. I currently have Michelin Pilot Super Sport A/S Plus (245/45/18) tires and 99% of the driving is in South Florida so pretty constant 80-90 degrees and 0% chance of snow. I want to go a smidge wider and just finished an online chat at the Tire Rack website. He told me I could go to 255/45/18 and they will be fine on my car.

So here is my question (really a few questions).
Specs for both sizes:
The 255/45/18 has a tread width of 8.7" and section width of 10.1" and 769 revs wheel range of 8" - 9.5"
The 245/45/18 is 7.7" and 9.9" respectively with 805 revs and a wheel range of 7.5" - 9"

First, is this even worth doing? IS the difference going to even be noticeable?
Will the 255's be so wide that the weight of the wheel (and car) may be pushing down on the sidewall?
How will the added width affect handling and grip? Will it be any different from the 245's?
I'm sure the MPG will change but will it be higher or lower and by a significant amount or just 1-2 MPG?
All ultra HP tires wear too fast with our M's but should I be worried the tread life will be only half that of the 245's?
Should I just stick with the size the car came with and shut my pie hole?
I'm hoping some of you lot with much more knowledge about tires and wheels can give me you opinions.

Thanks in advance!

[EniGmA1987]

I run 255/40/19 on my car with the stock 19x8.5 rims. The tires are just a hair wider than my rims are. For an 8" wide rim I'm not sure how well that would work because it would have a lot of overhang on both sides of the rim. I think you are right about the lip digging into the tire a bit
The grip should be pretty good since there is more tire on the road. I didnt notice any real differences in things like MPG or any of that though, and I dont think tire life will really take a huge hit.

[Larz]

Thanks Enigma! I was able to verify that the 18" wheels are only 8" wide. I love these wheels and if I could find them in a 19" size, I'd fancy doing the wheels and tires in 19", but so far I'm unable find 8-spoke chromes in 19" size.

Oi !! Over 150 views and only one response? Bloody Nora I even put the kettle on and nobody came round

[06M4.5]

I like to use 1010tires.com and the numbers show that a 255/45/20 would be wider but also taller too. Pending on tire brand, a taller tire may have a softer sidewall which will not make up for the wider foot print unless extra psi is used.

Not only will you get better performace of a 1" wider tire but you'll get better feed back, just keep in mind most complain about the M's front suspension and going wider may not be for everyone.



With great Florida roads I would just stick with the 245/45/18 that can stand up to all that heat & rain.

[Larz]

Thanks Freddie!
Mine would be 255/45/18 and I want the crisp handling like the Michelins where all you have to do it think 'turn left' and the tire starts moving, LOL. But, as you say, increased feedback through the suspension may not be for me. I'm beginning to think it's best I stay with 245/45. Looking at how much sidewall is already outside the edge of the 8" wheel (just a smidge wider than the wheel edge) and then adding an extra 1/2" on both the inner and outer edge makes me concerned about the sidewalls losing their stiffness well before the tread wears down.

[svard75]

Get a higher rated sidewall tire to compensate. It may increase road noise but you'll have the oversized tire without the extra squish.

[Larz]

ah HA! I didn't even think of checking sidewall stiffness. Thanks !

[szh]

In general, if the tire width range includes the actual width of your wheel, then you will be okay. So, if your wheel is 8" and the tire manufacturer says 8" - 9.5" for that 255/45-18 tire, then this is not a problem from a safety perspective. You can probably go 0.5" beyond the range (either way) without any serious compromises, although I would not advise it.

More than 0.5" off is going to be a safety hazard - your tire could come off the bead in a bad bump! People who use "stretch" looks are taking a serious risk, IMHO.

Technically, at the recommended tire pressure, there will be a slight more lift in the tire tread for the wider tire (since the wheel is 8"), so the contact patch on the ground may be quite similar for both the 255 and 245 tire anyway (for the same brand/model, of course). Remember that the Tire Rack specs for tread width assume that the tire is mounted on a wheel that is about in the middle of the recommended range.

From a handling perspective, both these tires are likely to be similar enough to be imperceptible in performance and looks and handling, etc.

From a load index perspective, as long as the tire load rating is 95 or higher, you will be fine. I prefer closer to 100 if I can get it in a particular brand/model - this has a slightly harsher ride, but safer for our heavy cars.

The one comment I would make is the rolling diameter - this will make your speedo inaccurate when going from a 245/45-18 to a 255/45-18. Just be aware of the change (can be calculated from the rolling diameter ratio's) so that you aren't inadvertently speeding. In an X model, as long as all four wheels are the same, as far as I know, the minor error in speed measurement will not affect the AWD system.

My one thought would be to look for a 255/40-18 size (as long as the load index is higher than 95!) if available in the tire you want, to minimize the error further. The lower sidewall height will increase road harshness very slightly, but also make turns and lane changes a bit quicker ... again, very slightly. However, lower aspect ratio tires also tend to have lower load index values, so be careful.

BTW, my current Michelin Pilot Super Sport (not the A/S model) have been outstanding tires - among the best I have ever used. Since I have a 7.5" wheel width, I stick with the 245/45-18 size as a maximum (the car came with 235/45-18). The tread wear has been very good as well - better than the A/S model I used in the past! Since you are in Florida, you might want to consider this tire too - the initial cost is more expensive, but the better tread wear (for me) has made it a better long-term deal.

Z

[Larz]

Thanks, szh! A very impressive, comprehensive education for me, that was!
I, too have never even considered anything but Michelins in the past and I have never been disappointed. The Conti's are also a great tire, but they don't have the grip in wet that I need in the puddle state - also lower rated in handling and noise control than Michelins.
However ... I have been checking out the Ventus S1 Noble 2 (99w, 500, AA, A) and I am quite impressed by the reviews and the video of the driving test at Tire rack. It's category is Ultra High Performance A/S. Here is a snippet of the info:

Ventus S1 noble2 tires use hybrid compound technology silica that combines wet road traction with lower rolling resistance and longer treadlife. This compound is molded into a sophisticated semi-rib asymmetric tread design that features notched outboard shoulders, intermediate and center ribs to deliver responsive handling and stable cornering in dry conditions. Four circumferential grooves and inboard Aqua Hydro Block technology provide efficient wet traction and braking. Carving edge grooves and 3D sipes promote wet road and wintertime traction without abandoning dry road response and handling.
The tire’s internal structure includes twin steel belts reinforced by a double layer of spirally wrapped nylon to blend handling, high-speed durability and uniform ride quality. Sidewalls are tuned with high-hardness bead fillers and casing plies that promote handling, steering response and ride uniformity. The tire was developed using 3D vibration analysis technology, which produces an advanced mold profile that delivers uniform contact pressure across the footprint to promote even wear and secure braking performance

It out-perfomed Firestone Firehawk, General G-Max, and Goodyear Eagle Sport competitors. It wasn't tested (at tire rack) against Michelin because the Ventus is in the next-lower price range, but the survey ratings for the Ventus are ALL higher than the Michelin Super Sport A/S 3 (latest version of the Super Sport) in the driving test where Michelin WAS tested.
Ventus had the best handling AND grip on the track for BOTH wet and dry, and the lowest tread noise of all others in the driving test.
Ventus ratings from the buyers who are actually driving on them: Hydroplainng resistance: 9.1, Dry traction: 9.2, Wet traction: 8.9, Ride comfort: 9.2, Noise comfort: 9.1, Treadwear: 8.1 *** all higher than Michelin driver ratings ***

I will be having whichever brand I buy installed at Tires Plus near my home and they offer a 30-day return policy if I am not happy. I can take these back and buy the Michelins if these Hankooks don't perform to my liking.
I'm seriously leaning towards giving these Hankooks a go. Even if they don't wear long like the Michelins, they are about $50 cheaper per tire so I suppose it's all relative, innit?

[EniGmA1987]

Hankook's are some great tires. I have not used the S1's personally but the V12 EVO's are my "stock" tire I have always come back to. They outperform the conti DW and DWS' in dry handling for me. We only get rain for maybe 4-5 days total out of the year so wet handling is not an issue for me.

[Larz]

Hankook's are some great tires. I have not used the S1's personally but the V12 EVO's are my "stock" tire I have always come back to. They outperform the conti DW and DWS' in dry handling for me. We only get rain for maybe 4-5 days total out of the year so wet handling is not an issue for me.

I was very surprised to hear things about the Conti's (DW & DWS) that could make one thnink they aren't great performers. However, lots of members use them and they can't say enough good things about them. I suppose it's a subjective thing and maybe the test drivers on tire rack website 'feel' differently. I refuse to believe that Conti's are sub-standard in any area but like every tire, they have a slew of avid fans and also some non-fans.

[szh]

The Continental DWS and DW are indeed excellent tires. No doubt about that and I will not ding them at all. I went through two sets of DWS's recently just prior to this last change. In terms of handling, wear and noise, the Michelin Pilot Sport A/S (the previous generation) and the DWS are amazingly similar on my car.

However, after trying the Michelin Super Sport this last time, I will definitely go with them again in the future. After 12 or 13k miles so far, they are still only down about 3/32" in wear ... which means that they will likely last about 50% to 60% longer than the Conti DWS or Michelin Pilot Sport A/S. I should be able to get about 32k miles (estimated) on them, where the DWS and Pilot A/S were done after just over 20k to 22k miles.

The Super Sports are quite a bit quieter than the DWS and Pilot A/S, particularly after 10k miles, and do handle better in wet weather (braking and steering) - my hot button for tires! These tires feel like they stick in wet as well as in dry. Very comforting!

Just don't use them in cold weather ... anything even near freezing (below 35 to 37 F) would be a bad experience for any summer tire! They would get hard as a rock and slide ...

Z

[szh]

I do not have any personal experience with Hankook, Dunlop, Fuzion, and some other fairly recognizable brands though, so I cannot comment on them really. Please take my comments below in that context.

With brands other than Michelin, Continental, some Goodyear models, Pirelli, Bridgestone, (and some other well-known brands), my concern is usually not how well they perform when new, but how well they still perform after 5k to 10k to 15k miles ... assuming that the tread is still more than 4/32").

When sidewalls flex, poorly made tires sometimes break (or fray) the nylon, metal and kevlar belts inside the tire and you can't see these issues! These broken and frayed belt pieces then move inside the rubber a bit as you drive, and cause the tires to not stay balanced for sufficiently long periods. Then, the unbalance causes people to think their rotors are warped because of vibration when braking!

In general, after a tire has used about 1/3 to 1/2 its tread life, if that tire requires re-balancing every 1.5k miles to stay vibration-free, then the tire innards are suspect, IMHO ... and likely to cause problems.

As an example, there is a cheap "house brand" that Discount Tire stores push heavily, called the Yokohama AK420 or 520 (has changed numbers recently) that is a dangerous tire on our cars! If you do a search for that model at NICO, you will see some horror stories of unexpected tire blowouts.

That is a serious no-no ... a good tire should just normally wear down without problems (assuming no road damage, of course!)

Z

[Larz]

That is such an important point! I already know Michelins keep their strength from day one till they are worn out. My current set of Pilot Sport A/S Plus are nearing the wear markers and they still handle VERY well with crisp turns and maybe even a little quieter than new (probably because shallow tread = less road grip = less road noise). I just mind how I drive in wet or slippery conditions because I know I don't have as much tread anymore. I have noticed slight cupping and tiny nicks or notches on the leading edge of the tread surface along the sides. The Tire guy where I buy mine told me that in areas like South Florida where the temps remain high nearly all year, all Michelin A/S models are known for this as they lack the compound found in high performace summer tires to prevent this. He told me that it's not a major concern long as the tire balance, rotation, and alignments are done on schedule. In fact he told me that with my tires being near the wear bars, he is surprised the cupping and nicks are so minor.

As for the Hankook Ventus 1 Noble-2, very few reviews could be found over 15,000 miles but so far no reports of sidewall weakening, no changes in handling, road noise, stopping distance, etc and all say they will buy this tire again.
I strayed from Michelin only once, for a set of Coopers (an expensive set mind you) on a range rover. After about 4 months I could not stand the road noise, and missed that Michelin confidence you have when turning or in spirited drivng. I ate the cost and went right back to Michelins. I am 90% confident I an going to give the Ventus a go and I will report from time to time as they wear. I'm only willing to try them based on the ratings being so much higher than Michelins - still can't work out why they are less expensive (by about $30 per tire) if they are so great, but seems I will be finding out soon enough. I'll report back as they wear and will definitely report if I have to exercise that 30-day option to dump them and get Michelins.

[kmiles]

Rather than start a new post, I have a tire safety question. Yesterday while traveling on I-5 I heard something rattling around in my right front wheel well and the car suddenly started pulling to the right. I was doing about 74mph and slowly pulled over onto the shoulder and found the tire completely flat and looking a little bit shredded. I put on the spare and drove to Discount Tire. I have Pilot Sport A/S Plus and they said that it required replacing, which they did at no cost to me.

My question - the tires are about 8 months old and had about 14,000 miles on them. The tread depth difference between the new tire and the other tires appears to only be 1/32 inch difference from my left tire to my right. That doesn't seem like much - should I be concerned? I have the AWD M35x model. I was impressed with how little wear I had after 14,000 miles.

The other thing that was interesting is that the tire monitors/monitoring systems didn't really alert me in any way. I'm guessing that the little tiny yellow tire light came on (at least it was when I started driving on the spare), but I would have expected something like an alarm, beep or major message on the display panel when the tire pressure went to zero.

[Larz]

A similar situation happened to me on the way up to NY in November. I detected a 'different' feel from the fonrt end that Fetucini quickly determined was caused by driving at 95 (she goads me about speed). I used the onboard comp to check tire pressures and the right front was reading at "19" !!!
I actually yelled out loud "how can I lose half my tire pressue and not get a warning?". And as just as I finished that sentence, I noticed a tiny lilttle icon in the bottom of the temp gauge that looked like a flat tire with an exclamation point in it. It was the exact same colour as the rest of the dash, just hiding there silently like a bloody church mouse!

What a confounding, barbarically and utterly STUPID design that is !! My car is travelling at break-neck speed on the motorway and is about to lose a tire and possibly all control, ending in any number of unpleasant consequences and the best idea Infiniti could come up with to alert me to this catastophic disater was a cute little tire icon in a part of the dash where one seldom looks? NO warning noises, NO flash of info on the center screen, just a cute little amber tire graphic ???

I pulled into the rest stop which luckily was coming right up. I called my road service and they found a large screw almost in the center of the tread surface. A quick plug and some air, and we were back on the motorway at warp-one.

[EniGmA1987]

There should be a long beep every so often. Mine beeps anyway. Had it happen twice to me, once right after leaving America's Tire when I pulled out the driveway and my car notified me that one tire had 29 PSI. Another time I got a nail in a tire and it beeped at me almost right away, but my pressure was already down at 14 PSI when I checked at the stoplight I was coming up to. By the time I left the stoplight I had 0 PSI in the tire.

[Larz]

You have an 06 and I have an 07 but I seriously doubt they would have dropped the beep function in my year. Perhaps my beeper went titz-up? I'll have it checked when I get my pedal recall done. Thanks for letting me know!
Of course, having my fav XM station (BPM #51) cranked to near Geneva Convention torture levels may have drowned out my little beeper, LOL.

[kmiles]

When my tire went flat, I never heard a beep on my 2007 M35X. I didn't have my radio on at the time that it went flat, but I was on the phone - hands free. I then had to drive about 15 miles to the tire shop on the spare. The little yellow tire light with the exclamation point was on, but no sound and no beep. I'll look into the settings to see if it something that maybe I turned off.

[The00Dustin]

My 06 M45 has beeped when the tire got low on two different flats. Good thing both times, too, because I was near a pullover point and it would have been bad to pass it. I can't imagine a 2007 not doing the same, yikes.

[Ilya]

Didn't see this posted, but this is a good tool I always use to determine if a size I am looking at will effect my speedometer so I can make up for it by lowering or raising my speed, etc.

http://www.miata.net/garage/tirecalc.html