Roen

I'm currently in the process of building a car to a points-driven classification system.

Basically, these are my mods:

RB Duct and Intake
Hi Flow Cat
RB Catback
5.125 Gears
Considering either RB Header or DPT Flash
Coilovers
Clutch / Lightweight Flywheel

So basically, nothing too powerful. I'm looking at Hoosier R6/A6 and am wondering what's the most optimum tire size for a car making the kind of power this car is going to make?

Also, will 17's fit over the stock brakes?

steve2tails

You can try searching tirerack.com I know they do sell the Hoosier R6 & A6 and good luck.

TeamRX8

iTrader: (25)

how did you determine that the mods listed are optimum?

paimon.soror

iTrader: (15)

I didn't see any claim of his current mods being optimum .... i think he was only asking for the optimum tire size

Huey52

iTrader: (2)

I would say the quintessential 245x40x18 upgrade. Not too hot, not too cold, just right.

Roen

I'm wondering if overly wide tires will hurt me on the straight due to increased rolling resistance as compared to a slightly narrower tire.

I'm considering the following in the front: 225, 235, 245
and in the rear: 225, 235, 245, 255, 265

I'm thinking I should stick to a square setup as I don't have the power to justify staggering the sizes.

Huey52

iTrader: (2)

Although wide tires do provide add'l contact patch area and thereby grip, you'll find they also more resist change in direction and you therefore lose some of the nimble handling. All design is compromise.

Staggering is not a good idea on this car unless you're just looking for aesthetics.

Roen

Most of the tracks that I run on only have a few corners that require change of direction, and nothing that quick like an autocross. Still 245 all around seems like a good idea?

Huey52

iTrader: (2)

^ There's a reason that 245x40 on the stock 18x8 rims is the most popular tire size upgrade.

Roen

245 on 8" wide rims is a bit too wide for me, I'd have to move up to 8.5 inches at least.

paimon.soror

iTrader: (15)

something about the above post doesn't make sense...

Roen

245 / 25.4 - 1....Is that number closer to 8 or 8.5?

It's always been my quick calculator for fitting tires onto wheels.

bse50

245 wide tyres will do just fine on an 8j wheel.
There's a notable car manufacturer out there that had some cars with 255 wide wheel mounted on 8j wheels

Roen

It will be "fine" just like 225's are "fine" on 7's, but they roll over in the corners when you get on the track. Would like the extra sidewall stiffness from the wider wheel.

bse50

You can use a lower sidewall to reach the same end results
Wheel and tyre choice should go together and implemented according to your suspension setup.

jasonrxeight

I found 245/35R19 on R3 wheels is a bit soft than the stock 225/40R19. seems like the car changes direction with a delay. not as crisp as before.

Roen

Now if only manufacturers would agree with you.....not too many smaller sidewall sizes if any available on the market. Perhaps you could share some examples?

bse50

Car manufacturers choose the tyres mostly thinking about NVH and overall comfort.
Tyre manufacturers build what the market demands.

Just google 245/35 r18 tyres and see the available options btw. I use 245/40 tyres on an 8J wheel (i'd rather go up to 8.5 but that's another point with another reason) without problems.

Roen

I looked at 245/35 awhile ago.....there's not much...I would also consider 35 too tall to get rid of the extra sidewall flex from using the narrower rim.

Tire Rack only carries the Ecsta XS which is a horrible tire in the wet.

My point is, sure you can trim sidewalls, but you're not left with much selection to maintain slighty better than poor sidewall flex, or you can get a better compound with poor sidewall flex.

Or you can just go up a half inch or inch on the wheel and solve all your problems for a bit of cash.

I can't speak for 245, but 225 on 7" vs 8" on a track, the wear pattern on the 7" was all over the place, but it was nice and uniform on the 8". Both cars had similar alignment settings.

bse50

Your math is all over the place.
Each tyre manufacturer states the min\max wheel width for its tyres width. Take that as a safe rule of thumb and adjust according to your needs.

Roen

My math is all over the place because I gave an example of a different wheel width? Ok.

If all I needed was a min-mix range of widths that are recommended for a tire, I could've just read a guide. The question at hand, is what is optimum, not what is recommended.

bse50

245/40 for track use is more than ok then.

Roen

Thanks for the help.