disasterman

Expect to do a little racing relatively soon.

Trying to decide on wheel diameter and tire size.

How many sets of wheels for drys?
(I was thinking two, one to heat cycle new tires)

What are the popular set ups? Why?

I have some turbo twists 17x8 & 17x9 that I expect to use for rains clad with 245x45x17 and 275x45x17 - Is this reasonable?

993944S2

17" or 18" will work for dry race. I use 8.5" & 10" 18's for my S2. 245 front and 285 rears. Most of the front runners use this size. I would not use 275 in the rear for rains. I run 245's at all 4 corners for rains.

disasterman

I thought you had to be within one inch of stock width.

Giacomo

Listen to Don, he's fast on that combination.
As I understand it, you can go one inch beyond what was available as stock or as a factory option for the USA model run. Having said that I recently had a conversation with another S2 racer that was certain that no 17" option was available for the S2 thereby making 17" the largest legal wheel but I have never looked into it myself. The sizes Don lists do appear to be the sizes of choice, budget permitting.

jerome951

I use 2 sets of 17" drys (I'm too cheap to buy 18" wheels and rubber). One set mounted w/ either used Hoos or RA1s for practice sessions and the other set w/ fresher Hoos for qualifying and races. Having each set of the same configuration/size gives you more flexibility.

I use my factory 16" wheels for rains.

disasterman

The way I read the rules there is no limit to diameter, only width.

In regard to the 245's for rains on all four corners - is there consensus on that?

993944S2

Wheel diameter is not restricted by PCA. Wheel width is restricted to 1" above those available from the factory. 9" was available with the M030 option on the S2 on the rear. Thus 10" is legal..

993944S2

Thanks for the compliment Giacomo. I could use a little more HP on the back straight. I was loosing 8-9 car lengths on the leader...

mmporsche

Smaller wheel/tire combinations weigh less and cost less. By adding an inch in rim diameter you are adding 2 to 4 lbs. per corner on average. The only reason you should go with a larger wheel is to fit over your brake setup.

You definitely want two sets of identical wheels and tire sizes in order to benefit from your alignment settings.

Larry Herman

If you are serious about racing, the preferred number of wheel sets is 4. One for your fresh race tires (either previously heat cycled or not), 2 sets for practice tires so that you can optimize wear, and one set for your rains.

Wheels are a one time expense, tires are an on-going consumable and I would prefer to run my tires till they are gone rather than change them out because they may not last a weekend. Besides, I have found that I usually only buy a set of tires for a race weekend, and all of the worn stuff lasts for practice, DE's and such. Last year I ran 3 race weekends and 12 DE days on 3 sets of Hoosiers total. Not too bad.

Nader Fotouhi

18" is the prefered size for FEWC cars. 245/35 F and 285/30 R combination gives you the same diameter. Weight is an issue for 18", so buy the lightest you can afford. I use 16x7 OEM wheels and run 225 Hoosier wets on all 4 corners (fortunately they have sat on the trailer more than being mounted), but work great when I used them.

disasterman

Sounds like I have a decision to make. Understanding that 17's may weigh less, what are the advantages of 18's?

mmporsche

I am unaware of any advantage of going larger other than they look more modern. Look at F1 - the pinnacle of racing technology. They are unlimited in their wheel sizing because their brakes are not inside the rims. I don't know what size the wheels are in F1 but I believe they are 15" or 16". My knowledge comes directly from 3R racing in Colorado. They have been very successful in Speed World Challenge - Randy Pobst. The one thing you may want to consider is tire availability but there are plenty of 15" and 16" tires being sold today.

trackjunky

I switched to 245's on all four corners and was faster.

I can't see why you'd need 285's on the rear of a car that only puts out 217HP at the flywheel (250 for an "S") and weighs 2900-3000#'s with driver. I think most people over tire these cars. Alignment is really the key on getting the car to be very balanced. Hell, Cup Cars run a 285 rear tire and have about 100 more horsepower and more weight over the rear wheels.

Remember that the Turbo has a different R&P ratio than the S2, so you need to set the car up to compensate for the taller gears.

The World Challenge TC cars put out more horsepower and have a similar weight and usually post faster times than the average PCA racer. Most run 245's.

Veloce Raptor

World Challenge TC spec tire is 235-40-17, not 245.

Bill is exactly right about not over-tiring the car. It's a common misconception that wider tires are always better. They are not!