Proper Wheel/ Tire sizing basics

DUCE400

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Hello everyone!

I have been reading posts on this forum and decided to sign up, I am excited to be a part of the community. I drive a 2012 GT 500 SVT (daily driver/ stock) and have owned it for about a year now and am ready to begin looking into my first upgrade. Even stock I find that the car generates more power than the tires can handle so I am set on getting new tires and possibly wheels. But my question is, is it better to keep the stock wheels and simply purchase better tires or attempt to buy wider wheels? And if I go with wider wheels, how wide can I go and what tires would fit well with stock suspension and fenders? I have looked around on the forums and have found a tons of different opinions/ advice. Though I must admit I am a little hesitant to purchase anything for the car without someone explaining it to me one on one. Im not looking to drag on a regular basis but I like to know that the car will grip the road (as best as possible) if I feel a little froggy on the gas. Again this is my daily driver but I live in FL so I can get away with summer tires almost year round. Thanks in advance for any help you can offer!
 

Catmonkey

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I think the biggest range of opinions center around fitting a given tire size on a given rim width. All tire manufacturers recommend a range of wheel width for a given tire size. I can guaranty that you will not find a manufacturer that recommends a tire larger than a 285 for placement on a 9.5" wide wheel. So if you want to run a larger tire, you have to look at wider wheels. The important aspect of running wider wheels for wider tires is to familiarize yourself with the concept of wheel offset. Unless your wheel places the tire in the proper zones of the wheel well, you may not be able to run as wide a tire as you might like because it places the sidewall too close to the inner fender or the thread under the outer fender lip. Tire Rack has a technical section that can explain both of these concepts better than I can, so you might check that out.

Bear in mind that the wider the tire, or a mismatched offset with a narrower tire, the more likely you will encounter some amount of rubbing unless you drive below your car's potential. I've got a thread in the DIY section of this forum http://www.svtperformance.com/forums/threads/making-clearance-for-wide-tires.916691 on what it took for me to fit 315s. I've since gone to 325/30-20s.

The other thing you want to focus on is tire compound. Generally the lower the UTQG number, the sticker the tire, but the shorter the wear life. There are also a number of tire sites that can give you general fitment guidelines with a given tire size and wheel offset. Take some measurements of your existing wheel/tire combination as to clearances and see what works or how close you want to be with the fenders.
 

ShelbyGT5HUN

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The most important factor in grip, is compound. Run the stickiest tire you can. A narrower, stickier tire, will out perform a harder compound, wider tire. I'd recommend Michelin Pilot Super Sports, or their Sport Cup II. I'd stick to the stock tire sizes, and run either of these two tires. If price is a factor, I'd recommend, Continental's DW series of tires, in stock sizes.
 

DUCE400

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I think the biggest range of opinions center around fitting a given tire size on a given rim width. All tire manufacturers recommend a range of wheel width for a given tire size. I can guaranty that you will not find a manufacturer that recommends a tire larger than a 285 for placement on a 9.5" wide wheel. So if you want to run a larger tire, you have to look at wider wheels. The important aspect of running wider wheels for wider tires is to familiarize yourself with the concept of wheel offset. Unless your wheel places the tire in the proper zones of the wheel well, you may not be able to run as wide a tire as you might like because it places the sidewall too close to the inner fender or the thread under the outer fender lip. Tire Rack has a technical section that can explain both of these concepts better than I can, so you might check that out.

Bear in mind that the wider the tire, or a mismatched offset with a narrower tire, the more likely you will encounter some amount of rubbing unless you drive below your car's potential. I've got a thread in the DIY section of this forum http://www.svtperformance.com/forums/threads/making-clearance-for-wide-tires.916691 on what it took for me to fit 315s. I've since gone to 325/30-20s.

The other thing you want to focus on is tire compound. Generally the lower the UTQG number, the sticker the tire, but the shorter the wear life. There are also a number of tire sites that can give you general fitment guidelines with a given tire size and wheel offset. Take some measurements of your existing wheel/tire combination as to clearances and see what works or how close you want to be with the fenders.
good information, thanks for the reply.
 

DUCE400

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The most important factor in grip, is compound. Run the stickiest tire you can. A narrower, stickier tire, will out perform a harder compound, wider tire. I'd recommend Michelin Pilot Super Sports, or their Sport Cup II. I'd stick to the stock tire sizes, and run either of these two tires. If price is a factor, I'd recommend, Continental's DW series of tires, in stock sizes.
thank you for the advice
 

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