Tire Load questions

[Denis]

okay, so im looking into and pricing up a square setup for some track days/auto x next year.

in my quest to find good tires for this task i got to wondering about the load rating. i found this chart:

http://www.discounttire.com/dtcs/infoLoadIndex.dos

according to the chart for example, a tire with a load rating of 99 can support 1,709 lbs of weight at maximum pressure. now, we're not inflating these things to maximum pressure. which leads me to my question...

how do we know what load rating is correct for our cars? id hate to find some tires i like and pick them up only to find out they arent load rated for our heavy ass cars lol.

[Rudy@Tirerack]

Passenger tires meet there full load capacity at 36 PSI. You can check your Gross axel weight ratings on your door placard to make sure they exeed these values.

[Denis]

Originally Posted by Rudy@Tirerack

Passenger tires meet there full load capacity at 36 PSI. You can check your Gross axel weight ratings on your door placard to make sure they exeed these values.

so the idea would be to take whatever the load capacity of the tire is and multiply it by 4 tires and as long as thats higher than the weight of the car than we're good?

[rtcat600man]

I remember while shopping for my set-up, that some shops will not install a set of tires that do not meet what the factory recomends for "load"

I thought the number for our 5th Gen is 103.

Find a load rating at that level or larger and you should have no issue.

[Rudy@Tirerack]

No. What you should do is identify the Front and the Rear Gross axel weight ratings. In the case of a 10 Camaro SS these #s are Front 2203 lbs and Rear 2468 lbs. Take the tire load rating and multiply it by two and this number needs to exceed the higher of the two #'s. In this case they would need to exceed 2468 lbs. Normally the factory tires will exceed this # by a good safe margin.

Keep in mind if you were right and the load rating and the tires air pressure dropped you may no longer be making load and it can stress the tire and cause the tire to fail. So you do not want to cut in too close.

Some shops will not install tires that come with lower levels than factor and that is their option.

[SPCBA]

Good info!!
I ran the falken completion tire azeni rt615k or somehing in 18s that had a load rating in the 1800 pounds range
To the poster about shops not mounting the tires. If you just bring them the wheels they will most likely mount them on the wheel the you can mount them on the car. The shops wont go below factory specs which we all know these cars come stock with suv tires so the factory spec is reaaaaaalllly high

[Denis]

Originally Posted by rtcat600man

I remember while shopping for my set-up, that some shops will not install a set of tires that do not meet what the factory recomends for "load"

I thought the number for our 5th Gen is 103.

Find a load rating at that level or larger and you should have no issue.

Originally Posted by Rudy@Tirerack

No. What you should do is identify the Front and the Rear Gross axel weight ratings. In the case of a 10 Camaro SS these #s are Front 2203 lbs and Rear 2468 lbs. Take the tire load rating and multiply it by two and this number needs to exceed the higher of the two #'s. In this case they would need to exceed 2468 lbs. Normally the factory tires will exceed this # by a good safe margin.

Keep in mind if you were right and the load rating and the tires air pressure dropped you may no longer be making load and it can stress the tire and cause the tire to fail. So you do not want to cut in too close.

Some shops will not install tires that come with lower levels than factor and that is their option.

Thanks guys!

So at minimum the load index would need to be 88? A load index of 88 yealds a load of 1235. 1235x2 = 2470. Which exceeds that 2468 number. So anything higher than that load index would work?

I understand that you don't want to be right at the limit. But if I'm just trying to locate the minimum limit.

[Denis]

[So Cal Camaro]

Originally Posted by Denis

Thanks guys!

So at minimum the load index would need to be 88? A load index of 88 yealds a load of 1235. 1235x2 = 2470. Which exceeds that 2468 number. So anything higher than that load index would work?

I understand that you don't want to be right at the limit. But if I'm just trying to locate the minimum limit.

I don't think I would go below the 99 load index or right around there, because when you put them under stress on one corner like using for autocross or road courses. I do think the original tires are overkill on the load index and have run tires with a 99 load index with no issues.

[Fish-man]

-keep enuf load reserve. Tires will have better lateral capability when they are not at full vertical cap. Tires v-rated and up need a certain amount of load reserve to be able to acheive max speed. In OE land, the feds require a certain reserve at normal condition and placard inflation...not just max load and max inflation (either 35 or 36 psi for most pass car tires). Inflation beyond the 35/36 does not buy you add'l load capacity.

Keep in mind OEs will give a max axle load that includes load of people and cargo.

[Denis]

Well I'm looking at running a square setup for the track. Basically I wanna do 18x9 all around. Soooooo I'm looking at 275/50-18 Nitto NT05's. they have a load rating of 99

[Pro Stock John]

Bump, good read.