Originally Posted by polonus
Sure. That's why cars like Bugatti (21" in rear!), Audi R8, all Ferraris and Lamborghinis, Corvette ZR1 and many others high performance cars use 19 and 20 inch rims. Just for looks, compromising performance.
Of course you can buy "regular" Corvette with 18 inch rims, but no ZR1. ZR1 is "good looking" model, for performance go with C6 Coupe on 18 inch wheels.
I did too. And that is why I say you have no idea what you are talking about. You right - big difference. 18 inch tires are "comfy" - or, to be precise, little more comfortable on potholes then 19 inch tires. Better ride? Sure. Better performance? In your dreams.
Either you didn't drive back to back M3 with 18 and 19 inch wheels, or you didn't pay any attention. There is a good reason why you cannot buy any Ferrari or Lamborghini on 18 inch wheels and it is not looks.
And I'm not saying, that 18 inch wheels cannot perform extremely well, but when you compare tires 265/40-18 to 265/35-19 there is no way car will handle better on tires with smaller rim, taller sides. Difference may be small, but always that difference will be for 19 inch tire advantage.
...Unless, of course, ride quality is your goal. In that case I suggest you to buy a Buick.
Not sure why you are trying to call him out when you don't have proof either...
You want to compare a C6 Vette with a ZR1. Why does the ZR1 have bigger tires? The front ZR1 rotors are a good ~70mm bigger than the base ones, you realize that right?
So back to your point why you can't buy Ferrari's and Lamborghini's with 18s:
Originally Posted by polonus
That is some hard data, however it doesn't proof your point, for at least couple of reasons.
First VW Golf is available, as a factory option, with either 15, 16 or 17 inch rims. Test in Car and Driver shows, that handling in those size wheels is increasing with coming to bigger wheels, and even in sizes 18 and 19 road handling is better, then with tires size 15, or 16. Acceleration suffers, but we talking VW Golf with 2,5l engine. It will not be a problem with 420 HP M3
Second, those tested tires are bigger, when rims are getting bigger. In M3 diameter of the tire on drive axle is exactly the same on 18 and 19 inch rim. Tire Rack shows, that both original equipment tires have 790 revs per mile. So it doesn't look like car will suffer from slower acceleration, it will have exactly the same ratios and speeds on every gear, and, according to Car & Driver test it probably would have better grip in corners.
When someone goes over factory size rims, let say to 20" on M3, car may suffer poorer fuel mileage and, possibly, slightly slower acceleration, if diameter of the wheel would increase. However test in C&D suggest, that going within factory size wheels, bigger is better. Better roadholding and better braking. For slightly slower acceleration - more power in M3 offers the answers. In my case it is 600 supercharged horses.
Did you even read the article? The 18s had the most grip because it had the more width than the 15-16's:
" Increasing wheel diameter and width
, in turn, requires wider tires
with shorter and stiffer sidewalls, which we found will increase skidpad grip, but as our test shows, there is a limit to this assertion"
Not to mention they were different compounds too.
If the width is the same, why would a larger diameter wheel be better as you claim?
Having said all this, I have 19s on my car (OEM). They do LOOK better without sacrificing enough performance for me to go to 18s, unless I'm at the track. This is just personal taste, but I don't think 18s on stock suspension look good on M3's. Now if it was lowered, it'd be a different story.