I heard slight stretch gives extra performance. Is this true?

I am thinking about running 18x10.5 wrapped with 275/35 tire which will be slightly stretched. I know there quite a bit members here that autocrosses, please share your .02

 

A 275 on a 10.5" wheel is not stretched at all. Stretched is when the wheel is wider than the tire.

With that said, 275 street tires on 10.5" wheels puts you in a rough place: ASP or SM. Ouch.

 

^what he said

to elaborate further, a little stretch is ok, but stupid stretch like a 225 on a 9.5 wide wheel will only slow you down

 

I was going by this
According to that tool it is lil stretched.

Well I will be in street modified as soon as I leave novice class due to having an upgraded intercooler
So, whether I have 275s or not my future in autocross will be full of with loses

 

275 on a 10.5 is fine

 

If I knew that I was going to be in SM in an Evo X, then I'd choose a wheel for 285/30/18s, in case I ever got the bug to be thuper therious. So I'd be looking at 18x11s, instead.

Plan ahead. Buy once.

 

I was actually shopping for tires last nite and come to find out that 285/35s are only couple bucks more or a little cheaper than 275/35 depending on the brand and store.

So I was thinking about going with 285/35 as for my tires. Is there a reason why you said 285/30?

 

Here's the reasoning: With 285s, you'll have good grip. So, you want the torque to use all that grip. Ergo, for autocrossing, 285/30/18s, not 285/35/18s. Plus, shorter, so stiffer sidewall and lower CG. Also, every major tire maker offers a 285/30/18. Rather few make a 285/35/18.

 

I thought having that extra side wall helps a lot with the turns. Hmmm.
I will be using these tires on the street too when I will be doing anything requires more grip. Like trip to dragons tail.

Maybe I should stick with my 19s since I am running 275/30s? I can always get better tires.

 

I think that is the opposite man...

I am yet to find rs3, re11, starspecs or nt05s in size 285/30

 

Sorry. I was planning way ahead. I was assuming that you'll catch the bug in a serious way and will want Rs.

 

Pretty sure you can run ASP (last season it was BSP) with an upgraded intercooler. SM (Street Modified) will be a higher class with upgraded turbos and more mods. Theoretically SM is a tougher class because of the allowances but realistically they are both extremely fast and competitive classes.

If you're running either classes you're S.O.L. if you're not running R-Compounds. Specifically 285/30/18 Hoosier A6's or Kumho V710's.

19's probably won't give you the right gearing ratios.

 

A lot of the Asian manufacturers don't run past a 275 tire because the majority of the sales and street tire time attacks run a 265 or 275.

 

I was referring to 285/30s. This size is only available for rcomps...

285/35s are not an issue to find at all.

 

Trust me, I dont want to run in SM but they made it sound like I have no choice due to the mods I have on the car.

I will talk with the instructors before I move out of novice class to find the appropriate class that will suite me the best