I'm taking delivery of a new Cayman S in a few days and am looking for a light weight 18" set-up for track days. The new OZ Alleggerita's are great looking, light and well priced; definitely on my short list. Question: are there wheel and tire sizes that will work well with the Cayman and accomodate R compound rubber. There doesn't seem to be much in the way of R compounds available in standard Cayman sizes.

 

R888 and NT-01 shall have your sizes.

 

Figure out which class you want to run and this will determine your wheel & tire sizes. Class rules usually include the most available tire sizes.

 

OZ Alleggerita's are looking good if you want to stay stock. But if you plan on doing heavy hard track driving then you might want to wait. Sometimes new, light wheels even from known manufacturers develop stress cracks quickly in track use. The Kosei K1 was an example of this - light wheel at a great price but some people found stress cracks.

Another way to go is with CCW. They are pricey but they are light. I have CCW C10s on the Boxster. They are about 2-2.5 lbs lighter than stock in stock sizes (18x8, 18x9) They cost $2800 which is hugely more than the OZ.

I would stay away from 19" wheels as they only increase your costs for wheels and tires and weigh more. The short sidewall on a 19 does not improve turn in as much on competition tires as on street tires. So any advantqage 19s have for the street go away on the track.

As far as tire sizing - If you are going Hoosier - 255/35/18 front 285/30/18 rear either A6 (autocross ) or R6 (road race) compounds.

If you go Michelin - Pilot Sport Cup available in Front:235/40/18 , Rear 265/35/18 or 285/30/18 or 295/30/18

There are other options from Yokohama (Advan A048) Toyo (R888) Pirelli (PZero Corsa) and others.

There is no reason to go with exactly stock sizes.

 

Care to elaborate for the track newbies? I guess you'll go wider to gain more traction.

 

Actually I was thinking about tire sizes. not many tire manufacturers make 265/40/18s but they do make 275, 285 and 295s. Going justy a little wider and lower profile than stock is ok. As a matter of fact getting a tire that is wider but shorter than stock will lower the center of gravity and lower the gearing, giving you potentially better acceleration and handling.

Really the performance differences will be slight on track (more pronounced in autocrossing). The main thing I was stressing was not to limit your selection to exactly stock sizes. You broaden your choice by allowing by allowing 10-20mm wider and 1/2" shorter than stock into the mix.

Remember, track days are not racing. Ultimate speed is not what you should be focused on. Instead focus on getting a setup that is safe and not too far your skill level. Perhaps Alan NcNish can handle a loose car at 140mph but I can't so I will try to set my car up to understeer more than he would.

 

That is true. I suggest you review the rules and see what conditions are required for tires. If rules permit I suggest the Hankook Z214. Its a phenomenal tire that has proven itself in the Time Attack series with numerous victories. Its available in several compounds to cater to your exact needs.


If rules require something less aggressive keep an eye out for the Hankook Ventus Z221 TD. I know it is available in Japan right now and word from Hankook is that it will available sometime this year.

Ben
RSS

 

what if i already have the factory 19" sport wheels? the tire prices are brutal so i thought about selling the factory wheels in favor of some light 18", but when i started looking at the weights they weren't too different from the carrera sport wheels. everything seems to be in the 22-25 lbs range.

is it worth it to go for the 18" if i'm doing one or two DEs a year? or should i just keep them and pay the $$$ for better tires?

 

If you are new, start gradually. Using a slick or a close-to-slick R-comp will just 1) hide your driving errors; and 2) is dangerous to yourself and others in the track. Start with max-performance summer street tires that you can hear and feel, before you move on to light R-comp like R888 or regular Hoosier R-comp. You will learn better this way.

Forged wheels are stronger than the cast ones in the track. Factory wheels (although cast) are good enough. I myself and my friends never have any issue with factory wheels.

All others said about 19" is right. 19" is heavy/expensive and doesn't give you benefit in the track.

 

If you are doing only one or two DE a year, stick with max-performance summer tires and focus on the skills. Changing that one set of tires to any R-comp is DANGEROUS for streets, esp. in rain. Or if you like, have two sets of wheels: one 19" street setup like you have now, and the other 18" for the track.

 

loyayay has good advice about R compound tires. I think you should keep the 19" wheels and tires for the street and get a set of dedicated track wheels and tires. Buy th OZs ($1600) and a set of Max Performance Summer tires ($800-$1200) Sure its a lot of money, but racing is never cheap.

If you sell your 19" you will get perhaps $600 max for them and you paid over $2000. Also your track wheels and tires will get beat up. Keeping a set of separate streets will insure that you will have nice looking stuff for resale and daily driving.

One other thing - keep in mind that you may wreck or damage your car on track and you may even get injured or killed. Your insurance may not cover you or your car. While these risks are fairly unlikely they do happen. You should be able to accept the losses that you might incur. You might want to contact your insurance agant and verify what your policy will and will not cover BEFORE you need it. I don't want to scare you off but some people do not recognize the risks and are unpleasantly surprised when uninsured accidents happen.

 

One thing to look at is the diameter of the rear tires. Porsche now designs the car and systems around a 26.3" rear diameter vs. 25.5" all around. If you vary from 26.3" you'll have errors in your speedometer, odometer and may impact ABS, PSM, etc. For 1 or 2 DE, just stick with summer tires... I don't suggest R-comps, even the "light" versions until you are in the White run group (assuming Green is beginner, Yellow next, White, and then Black). Many chapters don't even allow them until you are in one of the advanced groups.

If you get 18s, you might look at the Nitto NT05 in 245/275 - I believe that's pretty close to the correct diameters.

FYI, I picked up a Boxster S for my wife and the 2nd use is for my kids to DE with (keep my 09 C2S for myself - plus I have race pads, R-comps, trick alignment, etc.). I was able to sell the OEM 19s with PS2s for $2k and picked up a set of 18" Cayman S wheels w/ PS2s for $1400. Will run the PS2s out and then replace with Nitto NT05 245/275.

 

Wow, some great info so far...

In moving away from stock rubber I don't want to disturb the inherent great balance of the cars. Moving to fatter rears would likely lead to greater understeer. On the other hand, MPSC and Toyo R888's work in stock front sizes and 265/35/18 rears. The rears are a bit shorter but shouldn't throw off the balance...

 

ahhh, once you add timing; absolute speed becomes, well, relevant...definitely a slippery slope...

 

this is all great advice. i've had a few track days at sebring in my built e36 m3, and the summer tires were perfect for my skill range so i'll be staying with those for a while. i had some nice SSR 17s which were nice and light (16.5 lbs). but when i look at 18s and 19s, everything labeled "lightweight" seems to be in the mid-20 lbs range. is that typical for a lightweight wheel?

also, what's going to be better for rotating mass? assuming the same final tire diameter, will an 18" with a thicker side wall be lighter than a 19" with a thinner tire (more metal, less rubber)?