Lately with lots of free time I've been getting distracted trying to work out future plans, namely wheel and tire setups for track use and if the cayman ever gets classed in STU. Something else on my radar for the future is scca time trials. All three potential rulesets (or lack of rules, in the case of track days) are open enough that the only real limit is what's able to fit on the car. A few weeks ago I took some fairly detailed measurements based on the wheels and tires I have to try to figure out what will fit on the car. I concluded that the setup that would use as much space as possible without risking hitting the fenders or having the tires poke super far out from the fenders was as follows:
front: 255 width tires, 9 or 9.5" wide wheels
rear: 295 or wide 285 width tires, 10.5" wide wheels
I'm also targeting an inch of diameter reduction from stock, front and rear. The current autocross tires are an inch shorter in the front and almost 2" shorter in the rear. While the gearing improvement is nice it looks a little silly and has the potential to cause handling issues.
Unfortunately, reality gets in the way sometimes. As it turns out, none of the 200TW tires really exist in a 295 width size. Well, a couple do, but they measure just as wide as 305s and I don't want to stuff a tire that wide onto a 10.5" wheel. Pretty much all of the 285 width options are either way too tall or way too short, and tend to measure narrow. Then there's the 315/18 and 335/18 rivals which are just way too wide. So that pretty much leaves me with the only easily achievable option being 305s on 19x11s. This setup should fit considering that it's the only option for a SS GT4, but I'm concerned that it won't look great and that that much rear tire will make it difficult to get the car balanced. So that makes me think the only real option for the front is to try to make 265s fit, another thing that I think will work but might not look great and might run the risk of a particularly large bump causing a tire to make friends with the fender.
There is some upside though, as 305/19 rivals are dirt cheap compared to any other 200tw tire in a comparable size, 18" or 19" diameter. This also means that I can share rear tires with my friend's GT3 (of which my part of our codriving deal is supplying tires) though since both cars wear out the rear tires first I'm not sure how helpful it is. But it does mean that I have used up tires sitting around for test fitting purposes.
So last week I was browsing ebay and came across a cheap pair of decent looking 19x11 wheels from a 997, with what should be the exact perfect offset. My math says +41 is the lowest offset that will clear the suspension, these are +51 which when paired with the 10mm spacers I have results in +41 net offset and gives me some room to play with to get the fitment perfect. They arrived today:
They're a little bit more beat up than the photos showed, but for the price and their intended use (which may well just be test fitting) they're more than good enough. The offset marking s are a little hard to read and there were at least a couple different offset versions of this design wheel made, but my highly accurate tape measuring of the backspacing worked out to exactly 51mm offset, so I'm pretty confident they're as advertised. I'll toss one on bare later this week as I'm swapping tires for the autocross events this weekend. If that looks like they'll fit, I'll toss some used tires on them and see how that looks. Then I'll have to figure out the front situation from there.