Not sure which spec sheet you are looking at Robbie. The one I am looking at says( http://www.hoosiertire.com/rrtire.htm):

SPORTS CAR D.O.T. - RADIAL (A6 & R6) P245/40ZR15 Recommended rim width: 8-9.5"

So, you don't have lots of 9 inch that are no good, including the 2 sets yoou just had made up. And, not only can you use your 9 inch rims, you save $40 per tire, you can run the same tire front and back making it cheaper to own the needed wheel inventory, and extends the longevity of the tires by being able to rotate front to back, and easier to set up the car vs the 275.




Where's it coming from? That would be me, part of what I do with the rules as the National Director and rules maker for the series is try to make the rules better each year. In this case, less expensive is deemed to be better.

Hard for me to swallow this rule change in the 11th hour Is 15 months away from implementation really the 11th hour? Not in the race rule making world. Especially with tires which are an expendable item that from year to year change based on the product that manufacturers provide. When we first started everyone was using 205 and 225 x15's. Thats bumped up alot over the years. Drivers adjusted. The favored diameters have gone higher then back lower. Drivers adjusted. Profiles have gotten lower, compounds have changed. Drivers have adjusted. Tires are a moving target that racers adjust to based on available product.


Is anyone complaining. Yes, drivers complain to me all the time about the cost of racing being too high, even in the 944 Cup. Drivers often tell they come to this series and its classes because of the prospect of spending less on their race hobby. Here is a chance to make a difference in the cost of racing. The SP2 uses about 750 tires per year. If half of those tires are 275's, then 944 racers save or can put to better use about $10,000 to $15,000 per season by using the 245's. That's good for racers and makes the series more attractive.

Yes, one of the goals with this change is a better standard for tech purposes.



SP1 is not a class supported by Cup. We do not control or have any influence over SP1. We don't write the rules for the class. We have no SP1 Champions. We acknowledge cars in SP1 as legal Cup cars as they fit within the parameters of SP2. SP1 has been a series or class in competition for 944's that club race since its inception, and remains as such. Pointing 944 racers to SP1 for any reason is counterproductive to the Cup series.



What would be the cost to a racer of changing to 245's from 275's, other than lower costs of the tire itself? That is, what would change in your suspension setup and what costs would you expect to occur changing to a tire 1.1 inches narrower and the same diameter and the same compund? Would there be a need to buy new shocks, sway bars, springs, bushings?

What would change in driver ability and what costs would you expect to occur because of this change? Will a driver need to pay for coaching to able to drive a tire 1.1 inch narrower with the same diameter. Will a driver need to spend hours of track time to drive a tire 1.1 inch narrower with the same diameter and the same compound? Is there some other cost to driver ability I am missing?

Unless there is going to be a spec tire size, and based on this and the tire manufacturer thread that appears to not be the case, then I believe the limit should be wheel size. There is always a slight variation from manufacturer to manufacturer on actual tire size and it would be foolish to be DQ'd because you got a set of tires that were 1mm too wide. The wheel size is easy enough to measure by a scrutineer so that shouldn't be an issue.

I had planned to get my wheels widened when the funds became available but now maybe not.

Also, for clarity, can you run 245s on the stock 7" wheel?

The 245 x40x15 fits a 8' thru 9.5"



The current rules for 2013 actually do have this problem about having many variations and by as little a .1mm. The change being made for 2014 corrects this problem by using the printed section width on the sidewall. Section widths printed on the sidewall are fairly standard from one manufacturer to another, e.g. you won't see a 245 mm then a 246 mm. Like any other spec, drivers need to know the rules and buy accordingly, but with this change the spec is easier to get right for drivers and techs.



The ease of just looking at a tire sidewall for the section width is much better than measuring the rim width. Any scrut can walk a line of 944's at the scales or on the grid and examine 100 percent of the cars for legal tires in a couple of minutes. The same effort to measure rim widths would be time prohibitive, and that's even if the tech happens to have the tool in hand needed to measure the rim ( which I have never seen at a PCA event). The easier the tech inspection, the more often its done, gets done correctly, all of which better ensures the field of cars is legal.













The wheel size is easy enough to measure by a scrutineer so that shouldn't be an issue.
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