adi_d

I was thinking of doing the cup front conversion for my NB 997.2 GT3. If I use 18x10 front wheels would a tire like NT01 275/40/18 fit? Anyone has experience running 275/305? What is the balance like? Mainly track driving. Definitely don't want slicks or Hoosiers.

bmwtye

It will depend on your offsets and ride height and suspension setup if it rubs at full lock or not. If it's not dialed in right you will need to move the radiator mount forward to avoid rubbing on that mount. I'm running 275 front and 305 rear on 19s and have no rubbing at all. You can see my build thread 2 thousand 7 | GTY3

thekid96

I would suggest 275/35/18 to minimize rubbing the radiator. Get the right wheel offset and suspension dialed, then see if you need to push the radiators forward.
FWIW I am running 18x10 et 30 with nt01 275/35/18. Had to push the radiators forward and still have very minor rubbing on the fender liner.

adi_d

Tye, of course I read through your build info, it is quite awesome. I am trying to stay with 18 inch wheels, as I would really like to continue using NT01 tires as a cost effective track solution. How has the 275/305 size impacted your street driving experience?


It definitely sounds like some customization is required, but at least it seems possible to run the 275 NT01s. Have you had a chance to track the car? How has the balance been with the 275/305 sizing? Any issues with ABS/TC at the 275/30 ratio?

bmwtye

275/305 hasn't had any ill effects on the street. The front end definitely has a lot more grip. I have no issues going lock to lock either and I didn't move the radiator brackets.

I'll be getting a set of 18" track wheels and will be doing the 275/335 nt-01 setup as I've heard it's pretty killer.

powdrhound

I run the NT01 275/35/18 and 335/30/18 on 18x10x13 wheels on a 996. With the proper suspension bits you can actually run the 275s on 10s without modifying the front fenders or running flares. I did relocate the radiators forward 1/2" for more clearance.

The 275s will really need a 335 in the rear to maintain balance. I run a large 65" Cup wing providing a lot of downforce and the balance is dead on with the 335s. I could actually use even more rear tire. With a 305 you will be severely lacking rear grip in my opinion.

thekid96

I will be tracking my new set up this weekend, not anticipating anything but less understeer.

CosmosMpower

Should fit with the proper alignment and wheel offset. I'd run a 335 rear with a 275 front. I'm going to try and make this fit on my .1 soon.

adi_d

Right, this would make sense to me, but not sure if a 335 would fit a NB rear end. Also NT01 only goes up to 315 in 18 inch size, and I don't have the cup rear setup (yet). My main concern would be the overall balance on the track, as the front would theoretically have significantly more grip than before. And the modification is relatively permanent as the fenders have to be cut/modified.

Maybe I am just artificially limiting myself based on tire choice, but that has been the most cost effective solution for me so far.

modoz61

+1 on the reply from Powerhound

you will also need to be careful with ensuring you match profiles correctly

I believe both the 275 and 305 are 35's on 18's which will cause you some grief with ABS and stability controls - ICE mode I believe it is referred to as.

adi_d

That is definitely a variable/concern as well. Currently I run 245/40 and 305/35 which is off the stock ratio, but have not had any issues with ABS and TC. I do believe that 315/30 would cause issues however, unless I turn off the nannies, which I leave on.


The 275 comes in 40 or 35 sizing, so the diameter is the same as 245, so in theory it should work with 315/30.


Either way, my challenge is that they are so many variables and hard to try them out before making the modification

powdrhound

Again, you don't need to cut the fenders to run the 275. Keep in mind that a 9.5 wheel is a must at the minimum, 10 is ideal. Don't even try a 9 as the tire gets severely pinched. 335 will work on a narriw body with the right offset. 12.5 is a minimum with a 13 optimum. 12 won't work as the tire is too pinched.

thekid96

Interesting. Ditto calls out 12" wheel as optimum for the 335.

powdrhound

I know that's what Nitto has on their website but I just can't imagine running the 335 on a 12". Not only would performance suffer but it looks extremely goofy. The 305/35 fits perfectly square on a 12" but the 335 is severely pinched. When I was doing the initial fitting to check clearances with the 275/335s I used 9/12s. It was bad. I ended up fitting them and ran them on 9.5/12.5s and that worked out Ok but still had a bit of a bulge. I ended up mounting them on 10/13s where the tires fit perfectly square. On a back to back comparison, the 10/13s performed better than with the 9.5/12.5s as the steering response was a tad sharper due to less sidewall flex. Small difference but noticeable. Ideally you always want to run the widest wheel possible to stretch the sidewall a little. Look at what an RSR runs, a 310 on a 14".

Here is what the tires look like on a 10/13.


[url=https://flic.kr/p/LFwuP9]


[url=https://flic.kr/p/JivujH]

F1CrazyDriver

Correct on what powdrhound is saying. you want to "stretch" the tire slightly. Not stretch C&C style. Hmm 335 on a GT3 ? sounds like a lot of rubber to me, imo.
The car does not have any of the TQ that a turbo car has coming out of a turn. For me, it wouldn't make sense on a gt3. Turbo -yes.