Hi, old 15" stock 215/65/15 95?, now G35 18x8 225/45/18 91w in front. Getting new tire soon, but will the current one safe to use?
thanks
different load index, is it O.K.?
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Q45tech
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1995 G20t 5 speed 334,000 miles 16" 2002 wheels - 205/50/16 Sr20ve vvl
Re: different load index, is it O.K.? (moshmoshi)
For safety important to meet or exceed oem load index.
In a wreck the finding of weaker than oem tire requirement proves negligent operation of vehicle. In theory a police officer or DOT officer can ticket or impound vehicle for unsafe operation with weaker than oem recommended tires.
A higher than oem index indicates a stronger tire which usually will have a longer life.
In a wreck the finding of weaker than oem tire requirement proves negligent operation of vehicle. In theory a police officer or DOT officer can ticket or impound vehicle for unsafe operation with weaker than oem recommended tires.
A higher than oem index indicates a stronger tire which usually will have a longer life.
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maxnix
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1995 Infiniti Q45t
2000 Infiniti Q45
Re: different load index, is it O.K.? (Q45tech)
Make that minimum OEM load index.Q45tech wrote:For safety important to meet or exceed oem load index.
Higher is OK, lower is not. V35 about 500 lbs. lighter than a G50.
Modified by maxnix at 8:15 AM 4/26/2008
Re: different load index, is it O.K.? (moshmoshi)
It's not a good idea. Think about how much weight the front tires see when the car is cornering even during normal on ramp type operation.moshmoshi wrote:Hi, old 15" stock 215/65/15 95?, now G35 18x8 225/45/18 91w in front. Getting new tire soon, but will the current one safe to use?
thanks
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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: different load index, is it O.K.? (Rex)
Max Cornering transfers about 1/3rd of opposite side weight or 400 pounds of the front which adds up: 1200 lbs static [non turning] +400 =1600 why the 90-96 Q tire has a max load of 1521......................but remember this load capacity is at max inflation pressure [44/51 psi].
A 51 tire with 35 psi has 69% of rated load capacity...................sitting still it is overloaded on the front with no reserve for turning or braking.
A 44 psi max tire is obviously less dependent on air pressure [stiffer sidewalls] to support some of the load 35/44= 79.5%.
To get the same amount of safety reserve on a 51 psi tire you would need to inflate to 40.6 psi vs 35 psi !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Obviously tire manufacturers have a secret extra load rating [so we don't get sued] or the tire would fail when you turned.
The question with a tire is how much more safety [ABOVE THE AMOUNT PRINTED ON TIRE] does Michelin use than a low cost tire?
Why Michelin cost more and have fewer failures after 2 years of use.
They use $3 more expensive stronger filaments which add 15-20% in durability. They hand and xray inspect each tire which adds $10-$12 which reduces a 1% failure at the extremes to a 0.1% failures ....10x safer.Unfortunately this $15 higher production cost get multipled by 3 or more thru wholesale retail chain.
You can find tires with a higher load index as opposed to Buying Michelin Premiums which might increase safety depending on internal contruction.
What Police cars do they run 97-100 index Goodyears on the CV which approximates a Q weight.....................1609 pounds vs 1521 is only 88 more pounds or 5.7% but it is enough to significantly improve safety and durability.
Here is a 128 page 2001 police car tire test that shows what to look for, notice they use NYLON which most passenger avoid due to winter stiffness problems.http://www.nlectc.org/pdffiles/tirereport2001.pdf
A 51 tire with 35 psi has 69% of rated load capacity...................sitting still it is overloaded on the front with no reserve for turning or braking.
A 44 psi max tire is obviously less dependent on air pressure [stiffer sidewalls] to support some of the load 35/44= 79.5%.
To get the same amount of safety reserve on a 51 psi tire you would need to inflate to 40.6 psi vs 35 psi !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Obviously tire manufacturers have a secret extra load rating [so we don't get sued] or the tire would fail when you turned.
The question with a tire is how much more safety [ABOVE THE AMOUNT PRINTED ON TIRE] does Michelin use than a low cost tire?
Why Michelin cost more and have fewer failures after 2 years of use.
They use $3 more expensive stronger filaments which add 15-20% in durability. They hand and xray inspect each tire which adds $10-$12 which reduces a 1% failure at the extremes to a 0.1% failures ....10x safer.Unfortunately this $15 higher production cost get multipled by 3 or more thru wholesale retail chain.
You can find tires with a higher load index as opposed to Buying Michelin Premiums which might increase safety depending on internal contruction.
What Police cars do they run 97-100 index Goodyears on the CV which approximates a Q weight.....................1609 pounds vs 1521 is only 88 more pounds or 5.7% but it is enough to significantly improve safety and durability.
Here is a 128 page 2001 police car tire test that shows what to look for, notice they use NYLON which most passenger avoid due to winter stiffness problems.http://www.nlectc.org/pdffiles/tirereport2001.pdf