S550 Staggered Set ups and Tire Diameter

[2017RedGT]

Regarding Staggered Setups on S550 GT. How important is it to make sure that the Overall Tire Diameter between the Front and Back tires are same or similar......Or is it not important at all? Can there be a difference of an inch between front and rear diameters or do you need to run tires that are as close as possible in diameter?

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[JustSomeGuy]

It depends what you’re doing with the car. For example, drag cars are often very dissimilar, cars for oval/circuit racing are more similar. Generally as long as they’re the same or the rear is larger you will be ok (don’t take that to extremes).

 

[Need4SpeedMotors]

Regarding Staggered Setups on S550 GT. How important is it to make sure that the Overall Tire Diameter between the Front and Back tires are same or similar......Or is it not important at all? Can there be a difference of an inch between front and rear diameters or do you need to run tires that are as close as possible in diameter?

On these S550 mustangs since they are rear wheel drive they are going to have a staggered wheel setup. Rear being big/wider than the front. For example we do a 20x10 275/35/20 front, 20x11 305/35/20 rear. The diameter is different but that isn't going to upset the car. Race track cars use a square setup, same sizing all around so the car is equally balanced. Drag strip cars use a bigger tire in the rear, smaller in the front for less drag for straight line. It ultimately depends on what you are doing with the car. The size differences aren't that important on a rwd car, you might be overthinking it. If it was a awd car then that changes things.

 

[Trace]

The added advantage of a square set up is the ability to rotate the tires.

 

[Angrey]

Doesn't matter one bit, especially when you consider what's actually available.

The bigger impact won't be the diameter as much as the aspect ratio and profile of the tire. In order to get larger you'll have to end up with a larger profile and that will change the lateral grip somewhat depending on whether you're thin or thicker sidewall.

But yeah, if you go with a 29" tire in the rear, it's going to definitely upset the suspension setup to be more spongey and floaty in the rear. Unless you're talking drag radials, most of the aspect ratio differences between front and rear are going to be 30 vs 35 for performance tires. It's once you start to get into 40 and up that it drastically changes the lateral hold and bite.

If you change the characteristics enough, you could end up with a setup that's either less oversteer, or even understeer.

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