OK, so I know I'm probably starting a flame war here. I have been trying to sift through the endless threads on tires sizes for racing(specifically AutoX), and now I'm totally confused. I have seen some people say that they can't find good competition tires for the 18 Rays, while I'm almost certain that we can go to 17's according to what the SCCA rule book says. Moving to 17's would open up alot more tires options. My main problem is that I haven't found any definitive answers so far.

Quote:
"12.4 Standard Part

An item of standard or optional equipment that could have been ordered with the car, installed on the factory production line, and delivered through a dealer in the United States. Dealer-installed options or deletions, except as required by factory directives, no matter how common or what their origin, are not included in this definition. This definition does not allow the updating or backdating of parts. "

I guess the only thing to watch out for is finding 17's that clear the brembos.

Any clarification would be appreciated.

 

Well, I think the rules are open to some interpretation and that is from where the debate stems. Here's the definition of the "Stock Class":

13. STOCK CATEGORY
Cars running in Stock Category must have been series produced with normal road touring equipment capable of being licensed for normal road use in the United States, and normally sold and delivered through the manufacturer's retail sales outlets in the United States. Car models not specifically listed in any Stock Category class must have been produced, and must have met the above requirements and must have been sold through normal U.S. dealerships, in quantities of at least 1,000 in a 12-month period to be entered in the Stock Category.
Except for modifications authorized below, Stock Category cars must be run as specified by the factory with only standard equipment as defined by these Rules. This requirement refers not just to individual parts, but to combinations thereof which which would have been ordered together on a specific car. Any other modifications or equipment will place the car in Street Prepared, Prepared or Modified Categories as appropriate.

Option package conversions may be performed between specific vehicles of a particular make and model, but only between configurations from within a particular model year. Such conversions must be totally complete and the resultant car must meet all requirements of this section. Alternate parts listed in a factory parts manual are not authorized unless their use is specifically referenced in the factory service manual or in a service bulletin for the specific model.


It looks like one would consider the different Z models as different "Option Packages." To me, it sounds like you may change your wheels to the size used on another model of Z, as long as you change all the other aspects of the car to match. So, if you wanted to use the 17" wheels, you'd also have to get rid of the Brembo's, the TPS, the VDC, and the spoiler and diffusers. This would make your car the same as the Enthusiast and would therefore fit within the rules.

I personally don't know this for sure, but I do know that if you are going to be in big races, those types of semantics will be an area of contention.

I therefore decided to use tires that were the same size as those that came stock with my Performance Z (18x8 all around). My race wheels use a 35mm offset, which is withing the +/- .25" tolerance allowed by the rules. Even though I'm a sucky driver and won't be in any big race, I figured that I'd just err on the safe side.

I'm running 265/35-18 Kumho V700's, and I've heard of people running 275's on the 17" wheels (which are 7.5" wide up front and 8" wide in back).

My tires seem to work pretty well, but I've still got lot's to learn.

-D'oh!

 

Man, I didn't read that part. When I started racing my car at the AutoX there was a guy who used to run a 350Z track, and he said he was running the stock 17's with Kumho tires. Now, that doesn't exactly follow the option packages rule you have quoted above.

Question: Do you run the V700's as your street tire? Or are you somehow bringing that set of tires with you to the race, and if so, how are you getting them there?

Thanks in advance!

 

I change to the race tires before going to the event. I did a 50 mile test drive on the mountain roads around my house (about 3/4 driving or so) and the wear was very slight.

After my first AutoX the wear was significant, so I decided that driving to and from the events would only marginally affect the life of the tire. I am usually driving 80-100 miles round trip to the events. Also, since I'm in CA I don't have to worry about rain in the summer, so it's not a problem to drive to events on the race tires. Now that it is starting to rain, I'm not sure what I will be doing. I've still got decent tread on the race tires, so I'll probably just drive easy to races where it's raining. We'll see how that goes.

I'm thinking of designing a little tire rack, or maybe a trailer hitch for the Z, but my "pit stops" take quite a while so I think for now I'll just keep changing them at home.

-D'oh!

 

I run the 275 on the rear and 245 up front, A model Hoosiers, on 18's(track model). Another guy runs 275 all around on 17's. Cobra Mustang rims will work on the non track models, one of our local guys does that.
Most of the people in stock classes at Nationals and Pro Solo run the stock rims so there are no arguments, in impound at the Nat's we had to take 2 wheels off one side so everyone could take a look at suspension, etc

 

we contacted scca headquarters a few months back. http://www.350zfrenzy.com/forum/show...&threadid=1550

basically, if you have a track model you need to keep the size wheels your car came with to stay stock class

 

Terrific! That is just what I was looking for. I had better start saving up for some nice 18" racing wheels!

 

you would be better off buying new street wheels, and use the ray's for race wheels.

 

Is that because it would be hard to find another set a 18's that are as light as the stock Ray's?

 

not only hard to find light ones, but to stay stock you need to have the same widths and offsets +/- 1/4". The rays are 8" wide in front and 8.5" rear, and there arent' many aftermarket wheels that come in that size.

 

!ikes that is a good point. Thanks for all your help!