RAudi Driver

So it looks like I'll be bumping from a 19" wheel down to an 18". Now trying to figure out what tire size to run. Realizing that I can't get a 305/35/18, what are my next best options.

Is anybody stuffing a 335/30 under the rear well? I only say that because it's he closest in rolling diameter to stock.

obsessedone

Hoosier R6: 245/35-18 F, 315/30-18 R is a well balanced setup and keeps ratios F/R diameters close to stock
In other tires selection of sizes available will dictate choice to some extent

aero997c2s

Have you looked for 305/40/18?

RAudi Driver

^^ None.

mdrums

9971. Carrera S and/or GT3
1st combo is overall a shorter/lower diameter than stock 19" however it keeps the front to rear ratio in check so ABS does not freak out. Also this size lowers the gear ratio for better acceleration slightly.

2nd combo is the same overal outside diameter as stock 19"

255/35/18 front
315/30/18 rear

or

245/40/18 front
305/35/18 rear

RAudi Driver

Besides the Hoosier, who makes a 305/35? The wheels will be pulling double duty so slicks are out of my equation, for the time being.

mdrums

RAudi, see my post...those are the sizes you can pick from in 18". Also only thing available in 18" for 997.1 cars for a streetable r-comp tire is Toyo R888.

obsessedone

For double duty street and track, Sport Cups or similar tires on stock 19s are a good compromise especially in a dry climate like yours. If you hit heavy rain or standing water slow down and be smooth. They are expensive but they wear well - probably twice as long life as Hoosiers on the track.

mdrums

I'm trying MPSC right now in stock 19" sizes and I'm not too impressed. R888 has more grip for front tires. I'm seriously considering moving back to 18" wheels with R888 I 255/315 sized.

obsessedone

I usually ran 19" Sport Cups in 235/35-19 F, 305/30-19 R and felt pretty balanced running 34F/36R hot. Some run pressures as low as 32/34 but little margin for error at those low pressures - need to heat up carefully 1st lap or 2 when cool as easy to roll onto sidewall before they come up to temp at lower pressures. Of course front grip effected by sway bar settings also... too stiff front or too soft rear reduces front grip. R888 very noisy for street IMO

mdrums

Yes R888 is noisey on teh street but who really cares on the drive over to the track for the day and back. I won't run any R-Comp tire as a everyday street tire except the MPSC which is way more of a street tire than true r-comp tire anyway.

obsessedone

Probably depends in part what "double duty" means to OP, "street & track", or "drive to track & track".

Have fun out there!

RAudi Driver

Street and track.

Nix this thread. just found out that the wheels are 19's and not 18's. Bummer, but I think I am still going to grab them. The only issue I can see is that the front's are 9.5" wide with what is supposed to be a correct offset for a NB GT3. Hmmmm.....