Spartan

I get so many PM's and emails about running hoosiers on the 991 GT3 that I would just like to make a post so others can easily search and get the correct information. There is also some poor information floating around here which can be corrected.

Hoosiers on the 991 GT3 work perfectly. We have run them for several events with zero issues or problems and the results are as expected. Amazing!

Here are the only sizes that work. Do not run other sizes

Fronts are 265/35/19

Rears are 325/30/19

Currently hoosier makes the front in R6 only and the rear in R7. R7 is the replacement to R6. There is no problem or issue running this combo. No problems with ABS, RWS, TC, etc. No problem with R6's or R7's on the Gt3. Hoosier will make the R7 in the front size sometimes this year. R7's have a stiffer sidewall and require less air pressure than the R6. Figure 3 pounds less hot. I like hot pressure at 35-36 for R6 and 32-33 for R7.

The rims are BBS 19's and are stock offsets. You must run rims in the stock offsets or as close as possible. 1 or two mm won't make a difference.

Here is a post I made last year about mods to the rear lower control arm to get the 19's to work along with info on the shims

https://rennlist.com/forums/991-gt3/...-prep-diy.html

If you have any questions please post them here so others can learn. I'm here to help in anyway I can if you want to run hoosiers on your GT3. There are no secrets or magic formulas to run these tires. If you have tried to run the sizes posted above and you find that your lap times are slower there is something wrong and its not with the tires. That would be the driver or the setup and both of those can be easily fixed!

Here is a picture since we all like pictures

MayorAdamWest

I'd love to hear about 19" rims that fit and don't cost a fortune. Also, are there any 19" rims that don't require screwing with the LCA bolt?

Macca

Looks great Spartan. Thanks for the data points. Very helpful for the focussed track guys. How are you finding the wing?

jasonfreed

Finspeed is an option - mine are being made as we speak.


http://finspeed.com/performance-wheels/

MayorAdamWest

Are they affordable and leave some space with the LCA? O.Z.'s are $3k

Mech33

Looks like they don't make a 19x9 (at least on the F14 and a couple others I checked quickly), so you can't get the OEM front wheel width.

dfin23

They do make a 19x9 in all of their wheels. I have a couple of sets.

jasonfreed

I think they will make you whatever you want.

Call Daniel, the owner, he's very helpful.

jasonfreed

Pricing is on their website - depends on how many options you add but they are not bad for what you're getting IMO.

I'm prepared to flip that bolt.

Does OZ make a 19" set that works?

Mech33

Oh, cool! Odd that they skip that size on their website listing, especially when they're all cut from billet blocks anyway...

Finspeed

When we get below 26 units of a any forging we pull it to avoid backorder situations.We do have the 19x9 in stock and more on the way.

mooty

I ran Spartans comfig, same wheel same tires (based on his pioneering efforts)
they work
clearance is tomy
no scraping yet
I hit every berm I can hit

Spartan

The BBS are very expensive but they are very safe and hold value well. I don't know of any other brands personally but jasonfreed just ordered up a set from a USA manufacturer so maybe he can chime in?

The LCA mod is not so bad and I wouldn't let that deter you from running 19's

Mech33

Hey Spartan, do you have any more up-close pics of your Finspeed wheels (including showing the caliper clearances)?

Spartan

Thanks Macca. When you start really moving in these cars you will find the rear end is very light especially high speed sweepers. Also its susceptible to snap oversteer as noted by fastlaneturbo when he first posted about the wing. Not super confidence inspiring is a good way to put it but this only comes out when you are really pushing the car.

Essentially the stock rear wing isn't high enough to do all that much. The crawford wing addresses this and totally changes the car. Much more planted in high speed turns and it gives you the confidence to keep the throttle down. My track mechanic set up the car at the track after putting on the wing and per his suggestions we went with a rake to address this. This fixed the front end looseness and push at turn out under throttle. Overall our car went down about 10mm rear and 15mm front height wise.

Please let me know if you have any other questions on the wing!