JRL

I was thinking of trying this tire, its shorter but as wide as a 275. Any thoughts on if this would work on factory 18x10.5 Z06 wheels.

Thanks,
John

66IISS

A few questions.

#1 - Why? I always thought more was better, especially in the way of tires. We are in a traction struggle with 315's...

#2 - a 255 is as wide as a 275? I don't think I've ever actually looked at a 255's measurements, but they should be about an inch narrower than a 275...

drivinhard

it's on my list to "test"

because of the short sidewall, a 9.5" or 10" might would fit better. we'll see

argonaut

Don't know specifically but just as a point of comparison - I have 275/35/18 Hoosiers (Koni Challenge scrubs) on my 18x10.5 and they are stretched.

drivinhard

the "special" 255 hoosier has the same 10.3" tread width as the 275/17 and 275/18.

The 275/18 Hoosiers fit fine on a 10.5". A vertical slightly pinched in sidewall works better than one that's bulging anyway.

In our world because of class/mod/tire points, we are limited to smaller sizes. Maybe not ideal, but in reality, we have gotten our cars set up to work well on 275 C91s and A6s. You will find most of our lap times +/- what a 315 shod T1 C5 will run.

JRL

Yeah, the reason to try is what drivinhard stated. To stay in class but have more points to use for shocks/springs or whatever.
I was wondering about the tire staying on that wide a wheel with the small sidewall. I'd rather not run smaller tires and next year I'll probably move up a class then can run whatever I want.

Thanks
John

RX7 KLR

Just an FYI, from the people I know that have run the 255, it needs a lot of camber, more than the norm for a Hoosier. A lot of RX-8 and Solstice drivers tried them, and they corded on the edge very quickly - on cars with -1.5 or more. All of these guys went back to the 245 or 285.

JRL

Thanks Jason, Good info.


John

Pumba

255 mm section width tires are designed for a 8.5 inch wide rim.

drivinhard

in general yes, but the 255/18 Hoosier has a 10.8" section width.

JRL

Hoosier specs show recomended rim width range for this tire of 8.5-10 inches. 10.5 is a bit wide but I'm running 275 now which has a similar width with no issues.

Thanks for your input,

John

jaa1992

Damn, I'll have to look at that IIRC TTB (where my car starts) is a 245, so I have to take points for width and tire type, being able to run a 255 on an 18x10.5 or 17x9.5 and keep the 25.5 diameter - hmmmm its an idea.

So who is going to try it first - Mark, cheetah, jason??????

JRL

The 255 R6 is 25.5 od, but the only 255 A6 has an od of 24.8.
I would want the A6's over the R6's but it is a shorter tire.

John

JRL

I'll probably go to TTS next year. Its a hair raising ride running on these bicycle tires

John

RX-Ben

Has anyone called Hoosier about this?
What would be the possible problems with a 10.5" wheel?
It would make wheel selection so much easier, and that 10.8" section (vs tread) width would get stretched to ~11.3".
Is anyone concerned about the load rating of the 18" 255s (1047lbs)?

JRL

Good questions, I will check w/ Hoosier.

Thanks,
John

drivinhard

Personally I think the whole "wider is better" thing is probably over-rated a bit. Actual size/shape of contact patch based on tire width, wheel width, is a good study. In our case, a sticky ~10" tire on a 3120 lb car is enough. I don't think any of my lateral G or braking numbers from the traqmate are really sucking hind tit.

At the end of the day, a properly matched wheel and tire size is more important than just cramming a bit 'ole fat tire on the x size rim. Anything more is diminishing returns IMHO.

Maybe at the end of the year if I got some extra Hoosier coupons to blow, we'll do a 275/315 speed test if Jeff will allow me to run a session or 2 in TTS heck I'd like to try 245/255-17's on some 9.5" rims, I think they'd be faster than most folks think.

fatbillybob

Really, If you have run both 275 and 315 what kind of things different are done with the set-up? I would not know any better and just run the same set-up on both. In T1 we are mostly running 295's and 315's

JRL

I ran 295 square last year. This year on 275's I softened to rear bar to settle down the rear coming out of corners. On 275's the car seems more unstable on the high speed tracks/corners and in all braking zones. You can still post similar times but to me, it makes for more "oh sh*t" moments

John

drivinhard

haven't ran 315's to compare. 295 square last year is as big as we could go. And i meant more than anything, than on an A6 we are limited to a 275, and with that as the constant, just keep nipping at little details on the car within the TT/PT ruleset to keep making the car faster.

The C5 T1 rules look really interesting this year, I would love to run one