ok, i'm running 225's and 255's and don't think they will handle my new GT500R. I don't know what my HP will be but Broken9 got 450RWHP on 14lbs & 93oct. I plan on 15lbs but on 91oct and HKS twin power instead of MSD. So, maybe I will acheive the same numbers at 1bar (dunno yet).

So I was thinking of getting Work Meister S1 in 18x9.5-F's & 18x11.5-R's with 285/35's and 315/30's I think it was. I know I will have to do fender flares for this. Otherwise I would do 255's in front and 295's in the rear. I am afriad of paying bank for the wheels and then end needing to go wider. Is there any way to figure out how much width I need? Maybe you high HP guys can tell me what has worked for you?

I'm not necessarily talking about taller but unfortunately to go wider you do have to go taller. I'm also talking more of street/track setup then weekend drag strait line. Porsche has extremely wide rears but they have engines in the rear. ok, but what about Ferrari, they have wide and tall 19's? Corvette's tires get wider as the HP increases, look at the new ZO6.

 

you can run 9.5 with a 275 or 285 tire that should handle the HP...once you go 315 you will need to be flared

 

I know 295's would be the widest without fender flares but how wide without them isn't the question. If I need to widen the body then fine, but do I need 315's or 335's to keep her *** from doing a Shakira booty dance when I mash the throttle pedal? ...what about turns instead of spins. I would prefer "NOT" to drift because of my tires being too skinny.

 

Like I said yo u should be fine with 275 or 285 tires, just how deep is your pocket in buying some good street tires...

 

GoRacer, Gene Felber got 18x11" +48 Kenesis w/ 295/30/18 Pirellis on a car w/ out flares. I've personally seen the car, and he did it by using aftermarket trailing arms, cutting (not rolling) the inner fender lip off, and running a conservative ride height with lots of camber. It's tight.

Gene noticed after the fact that there was still a finger's width between the wheel/tire and the trailing arm, so it's possible he could have used a higher offset and not required extreme camber and/or conservative ride height. Hard to say for sure, but I think that a 11" +52 or +54 might've fit. He also noticed that the Pirelli 295/30/18 tire happened to be a huge 295. As large as a 305 hoosier, and a full inch bigger than the 285/30/18 Pirelli on a 10" wheel he used up front. Another brand might not have been so tight.

Your other option is RaceLogic traction control....

 

Thanks for the reply but i'm not asking what I can fit without fender flares. I am asking how wide of a tire do I need for the single turbo I am installing. How do you determine the ratio of tire width to horse power? 500hp will not be fun if the car drives like it's drunk and wiggles it's trunk all over the place.

 

Well, I think the short answer is "as wide as you can get". I drove the car with about 400 rwhp, and it'll break the 295's loose no problem.

I'd decide how extreme a flair you think you want, and get what fits under it. I think the cars w/ Pettit flairs typically run 12" rears w/ 345/30/18's.

 

Bigger is better if you want rear traction. I had 275's on my '69 Camaro putting down 546 at the wheel and they did amazingly well. I would have thought that i would have been spinning them all over the place, but they actually stayed fairly well planted. I know it's a totally different car, but still...

From my experience with high hp cars, you should be fine with 295's. That being said, for a car with more than 400whp you can break loose almost any tire if you jerk the wheel and step on it, no matter how wide it is. With that much power you can screw yourself up no matter what size tire you're running if you're stupid about it. Another thing about an FD with high hp is that even if you're running 500 hp at the wheel, it's much easier to get traction than a pushrod V8 will be with the same hp as the rotaries don't make as much torque, so the tire isn't shocked so hard at lower rpm...or any rpm for that matter...as other cars would be.

In conclusion, my suggestion would be 295's. But then again, bigger is always better...and would be more forgiving if you do something stupid. But if you're an experienced driver than you should be able to handle the hp fairly easily with 295's. Hope that helps...

 

FWIW, MY FC made 467 RWHP. My toyo T1s 255/17's spun in 1st, 2nd and 3rd with just rolling on the throttle.

I then went to 285/18 S03's. on a good street, these held in 1st gear most of the time. 2nd and 3rd no problem. The thing is since these aren't particularly "torquey" it's the top end you get to worry about, which is a bit different from a V8 car.

I concur with the above statements that 285-295 range (with a good tire) should hold 400-500RWHP sufficiently. If you're worried about it, go ahead and go for the wider setup and flair/roll the fenders.... Especially if you are getting those wheels. In my expereince, people never want less power than what they currently have.

Good luck, I"m currently asking myself the same question for my 20b project.

 

The biggest factor is perhaps how sticky the tire is. Get very sticky tires and 275s will be fine. And by "fine" I just mean that the car won't feel on the edge all the time. You will still be able to spin the tires in first and second gear on hot, dry pavement. And any coldness, wetness, or turning will make 3rd gear another "tire spinning gear".

-Max

 

I am running BFG KD's in 275 (17x10 rim) in the rear and they hook up pretty damn well. First gear can still be kinda squirrely, but after that they really grip. Of course, when I see rain clouds I head for the garage.....