Wheel and Tire Setup

[w3ab1ak91]

Hi all,

Looking to get a wheel and tire setup for my soon to be FI 21 GT PP. I'm guessing ill be putting anywhere around 700whp down and want to get the most traction I can without going to a full drag setup and losing alot of cornering capabilites. I won't lie im nowhere near a tire and wheel guru and offsets and all that are not my specialty.

Here's my current thinking. The GT500 making 760hp is running a slightly staggered setup with 315/30/20 in the rear and 305/30/20 in the front on 11 inch wheels. I could mimic this setup with maybe a set of nitto 555, nt05, toyo r888, etc. However, I'd rather not go to a 20 inch rim I want to stay 19 or even downsize to an 18. I was looking hard at Project 6GR wheels, and not sure what offset to run either. And I am looking at lowering the car with the Ford or Steeda springs that work with Magneride.

So... can I stuff 305's in the front on an 11 inch wheel? Should I do 315 in the back or even 325? 19 or 18 inch wheel? What size sidewall?

Thanks in advance!

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[EFI]

So... can I stuff 305's in the front on an 11 inch wheel? Should I do 315 in the back or even 325? 19 or 18 inch wheel? What size sidewall?

Yes, but you will need 2-3* of camber to tuck them in behind the fender. Although not sure why you need 305s in the front to drive on the street, that's more of a track focused setup.

You want as much tire in the back as possible, so a 305-325 on 11-11.5" wheels fits easily.

18" wheels are preferable in your case as that gives you a bit more sidewall for straightline grip.

 

[sjmurphy34]

I'd stick with 18-19" wheels, the gt500 has 20's because it has absolutely massive front brakes. Not all 18's fit over the brembos that you have up front though, some like apex do though.

19's seem to be a popular size especially with perf pack cars. A good quality/cost ratio wheel option are all of the sve flow-formed wheels, can get them in 10 or 11in width and they are lightweight.

With that much horsepower you may not grip fully from a launch unless on a prepped surface.

 

[Ewheels]

@EFI summed it up perfectly. All good info


I'll add some detail since you asked about offsets.
Staggered:
Front options:
(18 or 19)x10 +35 with 285/35 tire
(18 or 19)x11 +50 with 305/30 tire plus 25mm spacer & extended studs (rotatable)

Rear:
(18 or 19)x11 +50 with 305/30 tire
11.5" wheel for 315 or 325 tires

19" wheels you can get from anyone
18" wheels that will fit over the brakes: Apex wheels hands down

 

[NightmareMoon]

Watch your tire selection very carefully. Compound matters a lot more than tire width. Nitto has some real crap in their lineup (old compound formulations and old designs) and the GT500 doesn't use Nittos BTW. The R888 is also aging tire design. I'm talking street and streetable track tires. Drag tires you're on your own.

Grip will be better with 19s or 18s IF they have taller sidewalls (the GT500 only uses 20s to clear the giant front brakes)

 

[w3ab1ak91]

Great info so far. So nightmare do you have suggestion for a good compound tire? I heard some talk elsewhere on the forums of Indy 500's and I know the GT500 runs the Michelin 4S's.

 

[NightmareMoon]

Yeah, the MP4S has good straight line grip, but I get what you're trying to do, which is stick 700rwhp and that's a tough job.

High quality street tires will be optimized for linear grip (braking and accelerating) because braking is the one thing people really need from a tire. The MP4S does brake/accelerate really well. Ford puts the Sport Cup 2 on the GT350R and GT500, but that's so they can have amazing lateral G numbers for the magazines. That's kind of true for other extreme performance summers street tires. They may corner better than the MP4S but they won't grip all that much better off a launch (a little bit more straight line grip, yes). At a recent track day I took my street MP4S which are a couple years old and they just aren't what they are when new, but I was shocked at how well they handled linear acceleration (in this case braking). really really strong performance there.

The really sticky tires track tires need heat to work (R888, sport cup 2 suck when cold). The grippy extreme performance tires which don't need heat to work (i.e. autocross tires like the Falken RT660) might heat cycle out after a year or less and loose their edge on the MP4S after that. Even the MP4S falls off with heat cycles. 2 or 3 year old tires are nothing near as grippy as new MP4S with recent date codes, even if they're low mileage 2 or 3 year old tires,.

Check out the Falken RT660. Even in a 295/35R19 it puts power down about the best I've seen in practical situations like coming out of corners. That tire will destroy any Nitto which isn't a drag radial. the RT660 in 305/30 and 315/30 sizes are hard to get, but should be available at some point if you can wait a while for inventory to return. You may only get 10-15k street miles on a tire like that. You have to pay to play.

 

[w3ab1ak91]

Good stuff. Price isn't really an issue. I just want the best performance I can get. I know its unrealistic to think any tire at that horsepower level will dead hook on an unprepared surface. But I want the best chance I got without being on a DR. I would even consider a DR, but they're awful cruising at 80mph on the highway and taking hard turns... forget it. So far you guys have me considering the 4S and the Falken, which I can wait as the supercharger isn't going to be installed til probably September so it might even be a next year thing. Now when you say the sport cup 2 and r888 suck in cold do you mean overall? Or just when trying to launch?

 

[NightmareMoon]

Good stuff. Price isn't really an issue. I just want the best performance I can get. I know its unrealistic to think any tire at that horsepower level will dead hook on an unprepared surface. But I want the best chance I got without being on a DR. I would even consider a DR, but they're awful cruising at 80mph on the highway and taking hard turns... forget it. So far you guys have me considering the 4S and the Falken, which I can wait as the supercharger isn't going to be installed til probably September so it might even be a next year thing. Now when you say the sport cup 2 and r888 suck in cold do you mean overall? Or just when trying to launch?

Some of the grippiest tires are dedicated road course tires, but they're usually optimized for a higher heat range (so they can perform in track conditions), so you need to heat them up to extract their potential. When cold (esp in cold weather), they can be worse than an 'normal' tire.

 

[w3ab1ak91]

Well id like to be as multi-purpose as feasibly possible. Will I run on a prepped drag strip once or twice a year? Yes. Will I run it at a track? Yes. Am I looking to compete in actual events in either? No. Its all to have fun. Plus I plan to take a road trip here and there to car events and such. Obviously if I was going purpose built drag or track race car it'd actually be easier lol. But whatever will be tolerable in most cases, but give me the best shot at least getting some decent traction out of the hole if I end up racing someone from a dig on the street.

So far I'm leaning towards those 4S's. And I know other item apply, such as maybe gearing down to a 3.31 rear end, some stiffer bushings and such.

 

[w3ab1ak91]

Also just checked out the Project 6GR Sevens and they don't offer an 11.5 inch wide rear wheel :/.

 

[NightmareMoon]

Also just checked out the Project 6GR Sevens and they don't offer an 11.5 inch wide rear wheel :/.

I saw that, I also was in the market for some 11.5" wheels and looked to see if P6GR had any. I think they used to have that, IDK.

That extra 1/2" isn't really a big deal, as I said, picking the right tire matters a lot more than a bit of extra width.

 

[w3ab1ak91]

Is throwing a 325 on an 11 inch rim an option or is that pushing it?

 

[sjmurphy34]

They do have 11.5" wheels, just make sure you click on the ones that say "R-spec."
https://project6gr.com/product/project-6gr-seven-gloss-black-finish-r-spec/

As for 325 on an 11 inch wheel, lots of people do it without issue however I think 305 is a better fit for 11in, but everyone has a different opinion. IMO, 325 is a better fit on 11.5 but it can work on 11 in wheels too.

 

[w3ab1ak91]

Gotcha, thank you!
So if I ran a 19x11.5 in the rear with 325 tires.
Could I run 19x11 in the front on 305 without rubbing?

Mind you ill be lowered about 3/4"

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