Sidewall Height or Aspect Ratio?

[Madlock]

The kinky combination of wheels, tires and springs has with the SVTPP has made choosing alternates a real bear. Not only do very few suitable alternatives exist for the OE wheels and tires, but the staggered setup really doesn't help matters either. I've decided to deviate from the SVTPP's 27.9" rear wheel in favor of Mustang's conventional 27" and have several ways of going about this.

 

This set of wheels and tires are meant to be my "around towners".

 

 

The simplest is to use a 19 x 10" Ford Racing SVTPP look-alike (which I have) for a 285/35-19 which takes ALL the size out of the wheel. However, I can also achieve the same diameter reduction by using the OE wheel with a 285/30-20 tire instead. Since so few alternatives exist for the 265/40-19 front tires, I'm likely to step-down to a 255/40-19 or even a 245/40-19 to both broaden the number of choices and restore as much of the SVTPP's more aggressive rake as possible.

 

In going through the various options, maintaining the rake stance became a challenge after amid what will ultimately lower the rear-end by 1/2". However, it's possible to maintain a very close diameter using a wider tire with a narrower aspect - effectively keeping the same sidewall height.

 

I'd appreciate any insight from people who've considered some of these factors - up to and including perhaps using a 2X5/30-20 rear tire.

[IA Shelby]

Considered yes but as of yet had not made a change. It will be when I buy another set of wheels in the 20. I want to maintain the same approx diameter. The downside with the shorter sidewall is some loss in ride comfort and handling,

[Wingrider]

Are you trying to save the tires for the track, or get more gear with a smaller tire?

 

Granted they don't stick well when cold but they are pretty impressive when hot and a smaller tire is going to make your traction problem worse. If you track the car more gear will also change your shift points- more of them.

 

I wish they were a tad better cold but I like the F1:G2 tires.

[89Saleen215]

I've been playing with this since I don't care for the short sidewalls (3.5") on the 295/30-20's I'm running. The height on the fronts (3.79") with the 275/35-20's look much nicer. To match the fronts I think I need to consider actually running a 295/35-20 (4.1") or the 335/30-20 (3.96").

 

The formula to play with to figure sidewall height in inches is: width (mm) x (series/100) x 2 / 25.4 / 2 = side wall in inches (ex. 295 x .30 x 2 / 25.4 /2 = 3.48")

 

Just remember when you're all done you'll need to figure out Revs Per Mile and set that in the computer to calibrate the speedo.

[Madlock]

Are you trying to save the tires for the track, or get more gear with a smaller tire?

 

Granted they don't stick well when cold but they are pretty impressive when hot and a smaller tire is going to make your traction problem worse. If you track the car more gear will also change your shift points- more of them.

 

I wish they were a tad better cold but I like the F1:G2 tires.

 

 

Neither - for their own sakes.

 

The F1 G: 2's are really good track tires - and what I'll continue to run at the track, even though the BOSS 302, and even 302S and the various FR500's run 18's and 19's with no shortcomings whatsoever. To be honest, I have very little idea why Ford went with a 20" rear tire for the SVTPP except for appearance's sake - or to maybe balance out the additional contact patch with the 265's up front to keep over/under-steer in check.

 

But I want a set of much better-mannered set of everyday tires. I actually wouldn't mind adjusting the shift points - doing away with 1st altogether.