Darth Evader

Other than appearance reasons, is there a benefit of using a larger 18 or 19" wheel vs a 17"? I'm just curious why all of the new cars (Mustangs/Camaros, etc) are being equipped with larger, heavier wheels.

Thoughts?

Legion5

40-45 profile is approximately the ideal sidewall stiffness of a sports car. Anything over that has a tire that flexes too much naturally. The Mustang with 19" wheels has 45 profile tires, so does the Camaro (45 & 40 ), so does the mustang with 18" wheels (45). So does the mustang with 20s (40 rear)

These actually provide some performance benefit on a clean smooth street at the cost of reduced performance on gravel and bad roads etc.

However the larger wheels on passenger cars started out as a trend for looks having nothing to do with performance and ended up luckily putting most sports cars with ideal tire sizes by accident. Very high end sports cars like BMWs and Mercedes actually use 35 profile tires now which hurt the performance rather than help it thanks to the trend for larger wheels.

Larger wheels were originally put on sports cars to clear larger brakes but what I'm saying is that they don't hurt performance in our cars and it's competitors. The wheel weight is an issue but on a street car it's not that important because there are 20" wheels that are lighter than 16" wheels, the steeda 20s for example or the Saleen forged 5 wheels which are also light wheels. so it depends on if you choose a cheap heavy big wheel or a light one more than anything in terms of weight.

Darth Evader

Great info Legion5, thanks!

Texotic

Like Legion5 said, the 18's or larger on these cars are required to clear Big Brake Kits.

Diabolical!

In my experience, my 18" fanblades were good for costing me 2/10ths of a second at the drag strip. I dumped them for a set of stock 17"s and couldn't be happier.

Argonaut

On race tracks a lot of guys favor the 17" over the 18" simply because of the cost of tires, at least that has been the conventional wisdom. But I think its changing. Several racing series are now using 18" and its getting easy to find 18" scrubs for $50 - 100 each. Plus - if you want/need bigger brakes you'll need the 18s.

Sleeper_08

I just had a look at the specs for Porsches USA and they fit 235/35 ZR 19 front, 305/30 ZR 19 rear on the GT3 and Turbos and it says the Turbo rims are Forged alloy 8.5J x 19 ET 56 front, 11J x 19 ET 51 rear. It looks like their reason for going to 19s is the brakes since on the Turbo it says -

"A range of optional 18- and 19-inch winter wheels (all snow chain-compatible) are available from Porsche Tequipment. Vehicles equipped with the optional Porsche Ceramic Composite Brake (PCCB) may only be fitted with the larger 19-inch winter wheels."

It would be interesting to see a Turbo with snow chains

mustangtestuser

I have the 17 inch wheels from the factory, however, I wanted to run a wider tire. 255/50R17 will work, but there are just so few tires offered in that size. It's a real oddball. I was pretty much forced to go with 18 inch wheels in order to fit 255/45R18. Tires in that size are more plentiful, generally lighter and usually the same cost, if not cheaper, than 255/50R17, after all.

The biggest problem is the weight. The 18 inch fan blades you mentioned weigh 26.5 lbs each! The 17 inch machined aluminum wheels are about 22 lbs each. Total weight with the stock 235/55R17 tires is about 50 lbs each. When you take into account the tires (maybe an additional 2 lbs or so), you're probably looking at an extra 6.5 lbs per wheel! That's a lot of extra rotating mass.

The only solution are light weight wheels. I have some 18 inch OZ Racing wheels that should be here soon. Total weight is 19 lbs per wheel. Total tire weight for the BFGoodrich g-froce T/A KDW 2 tires I ordered are 29 lbs per tire. That should mean a combined weight of 48 lbs. That's two pounds less than the stock wheels and tires with the same overall diameter while still running a wider tire!

The big downside is expense. Cost for the wheels and the tires was $2k, that's with a 17% discount on the wheels from Tire Rack. I hope it's worth it...

Rubrignitz

I'll gladly sacrifice a few lbs rotating weight with the hp these cars output for the extra meat on the road. With my 275/40's fr and 305/35's rear (and the sticky DR rubber seems to help substantially) the car really sticks to the road like glue. It's very hard to get my rearend to let loose anymore in curves or when shifting gears. I'm really prepared for FI now.