Anyone running 30-series tires on OEM GT350 wheels?

[THX 138]

I just found a set of barely-used stock GT350 (non-R) wheels relatively cheap, and I plan to put a set of Hoosier R7’s on them for my track days this summer. Hoosier makes the R7 in both 35-series (295/35R19 & 315/35R19) and 30-series (295/30ZR19 & 315/30R19), for nearly the same price. (The 30-series tires are actually slightly cheaper.)

I’m leaning towards the 30-series tires, in part because they should have a slightly stiffer sidewall and in part because the smaller diameter will effectively give the car slightly shorter gearing, which should in turn help me take better advantage of the GT350’s high-RPM powerband. (No risk of running out of gear at my local track.)

Curious whether anyone here is running 30-series tires on factory GT350 wheels, and if so, whether you have anything good or bad to say about that combo.

 

[VoodooBoss]

I've run the 30 series R spec SC2 tires on aftermarket wheels and there should be no issues on the stock wheels. In fact I recommend it. The main reason why the R is quicker to 60 and 100 is the grip and lower gearing of the 30 series SC2 tires.

 

[THX 138]

Thanks, Rick.

 

[VoodooBoss]

FWIW I'd skip the stock wheels for the track and buy a set of APEX 19x11 square and run square 315's. That combo will be 10 lbs lighter per wheel and you'll feel it on track. Plus squaring up the car will eliminate the mild push it has in the stock staggered setup.

 

[THX 138]

Thanks for the suggestion. The Apex 19x11 EC-7's are a possibility for next year. They cost almost exactly twice as much as I paid for the extra set of stock wheels though. We'll see how the stockers with R7's do.

 

[DocWalt]

I've been running square 305/30-19 RE-71Rs for autocross use. The shorter gearing is noticeable as is the lower ride height (scrapes the splitter protectors leaving my driveway). The speedo is wrong, but on track, who cares?

 

[TrackRat]

FWIW I'd skip the stock wheels for the track and buy a set of APEX 19x11 square and run square 315's. That combo will be 10 lbs lighter per wheel and you'll feel it on track. Plus squaring up the car will eliminate the mild push it has in the stock staggered setup.

digging this one up as I just committed to a set of square 19 x 11 Apex Forged Sprint Line wheels and am not happy with the ‘stretched’ look of the 305/35s on my factory rear 19x11. Had been thinking about going 315 all around but wasn’t sure if that may be too much tire up front and should just stick with a 305/30 setup.

 

[JDee]

Personally, I would say there is no such thing as too much tire up front. That is the heavy end of the car and it does the most work, it pushes like a dog once you really get going and is the most limiting factor to corner speed. 305/30 square on 11" with 20-25mm spacers is the proven way to go. There's a formula to making these cars handle and that's a fundamental part of it. If you can make 315s fit square then that's even better.

 

[WItoTX]

digging this one up as I just committed to a set of square 19 x 11 Apex Forged Sprint Line wheels and am not happy with the ‘stretched’ look of the 305/35s on my factory rear 19x11. Had been thinking about going 315 all around but wasn’t sure if that may be too much tire up front and should just stick with a 305/30 setup.

I think you asked this on another forum, but if not, it really depends on what tires you put on. A 315 Yok is wider than a 315 660. We had to roll fenders to fit 315 Yoks. With those rims, going full square, you will need a 31 mm spacer with the Yoks. I personally would go to an OP hub with the longer stud bolts, but some folks are ok with a bolt on spacer. All depends on what you are looking to do.

 

[Bill Pemberton]

R7s work great and I only ran 30 aspect ratio when I had my GT 350. The one item I would politely suggest is most of us on TMO would argue against going with bolt on spacers ----too expensive a car to use a somewhat scary set-up. ARP studs are impossible to get for now , but that is the only way I would consider and be comfortable on the track. Track use is rougher on studs, banging over curbing at 100+ often and at some tracks even getting air, you must need solid protection imho.

 

[TrackRat]

Thanks! Advice is always welcome. What’s the solution in place of spacers? May not fully understand alternatives.

 

[TMSBOSS]

The Bolt On spacers are frowned upon. A solid, hub centric spacer which has the cars studs/extended studs pass through it are preferred. When the cars studs are hidden inside a "Bolt On" spacer, problems are more likely to happen.

 

[TrackRat]

Got it. Hub centrics already on order. Thanks!