Why 19 inch wheels as performance option?

[KGrGunMan]

I'm just a car guy who's put in a lot of time trying to make my own cars faster around a track. I can hold my own working on the drivetrain and other parts of the car, but my focus has always been on making a car handle well and how i want. So suspension and tires is where my real knowledge is. I worked my way up at the race track, trying to stuff tires that were the wrong size on wheels that were the wrong offset. My knowledge comes from 10 years of hands on trial and error, watching the stopwatch and seeing what made improvements and talking to friends trying to do the same thing.

One of the cheapest things that helped me set faster times is the alignment; people will very and disagree on specs but i've seen too many timing devices agree that I set my fastest laps with 0º toe on all 4 corners (and better tire wear) and a ton of caster. since this is going to be both a street and track car for me, i'm only going with -1º of camber, but i'll probably play with the camber and take some pictures of my car mid-corner and make adjustments to the camber. All part of the fun of modding cars, tweaking and playing with them to make them perfect for you, instead of the average joe.

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[KGrGunMan]

A couple of searches at Tire Rack finds 45 different tires in 285/35-19 (and 32 more in 285/35-18, which is still enough tire in terms of load capacity). These will mount nicely on wheels from 10" wide (a rather conservative choice) to 11" (if you're a more demanding driver).


Really, the only functional reason I can think of for 20's or even 19's is that you can't fit 18's over brakes much bigger than 14".


Norm

If you're staggering sizes front to rear then it might be fine, but if you're going with a square setup then 285/35/18 is way too short in overall height, so 285/40/18's would be a better height, but only if you don't have a GT-PP, because of brakes and rear tire size.
285/35/19's not a bad size if you have a non GT PP, but if you have a GT-PP then 285/35/19's are 0.8in shorter than the stock rear tires. That's a bit much for me.

I understand why everyone is so against performance 20's and I always said i'd never have 20's on a car, however in this specific case and for this specific car. 20's seem to be the way to go if you want: A. to clear 15in brakes, B. to have the most lateral grip possible and C. a height between 27 and 27.7in tall.

 

[Norm Peterson]

I don't think you could pay me enough to run staggered tire sizes on a Mustang for anything other than a few very short-term situations. Forget anything involving staggered wheel diameters.

We agree on A., disagree on the necessity for C., and the jury is still out on B actually favoring 20's (or 19's) over 18's given the same tire mfr & model, width and profile for all three diameters.

As far as speeds in gears goes, if "losing" 2 mph at 55 or 4 mph @ 110 really matters that much, that can be fixed with an axle gear swap (or perhaps a more thoughtful choice in the beginning). By way of illustration, 3.55's with 26" tall tires is so close to 3.73's with 27" tall tires that you'd never be able to tell the difference without instrumentation.


Norm

 

[KGrGunMan]

I'd agree, if the tire is the same and the contact patch is the same, then the smaller wheels are the way to go, but I have not found a tire that'll give me as much rubber as a 305/30/20 while still meeting my other needs.

My reason for not wanting to go below 27" tall is because that'll decrease straight line grip, both launching a 420+HP car and slamming on the stoppers at the end of a straight will be improved with a taller tire.

 

[908ssp]

Lots of opinions very little fact. There are 20 inchers that weigh less than 18 inch wheels and there are 20 inch tires that weigh less than 18 tires. There are no hard fast rules. And you can't assume people are comparing the same wheel in different sizes. Each and every choice has to be compared to to any particular choice not generalizations. I ran 20 inch wheels and 28.5 inch rear tires that weighed less than any factory option including the 17's.

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