Autocross: stock rims + tires or new rims+tires?

[Spencan]

I have been occasionally autocrossing with my local PCA since 2008, usually 2-3 times per year just for fun. I currently have aftermarket OZ Racing 18x8.5 and 18x10 rims with Continental ECS 235 in front and 275 in rear. They're great tires for street use and are ok for autocross.

Here's my dilemma: I want to be more competitive this upcoming year and get a better tire setup for autocross and I am debating these two options because cost is a concern.

1) Use my stock club sport forged rims- 16x7 and 16x9, and then get the ONLY tire option available, Yokohama Advan A052 in the stock 225/245 sizes for around $1k.

2) Find some used 17" rims and then have more tire options, but overall spend more money.

Money is a constraint because I AM a married high school teacher!

So, I am asking for opinions because I keep going back and forth between the two. Especially because of looking for used 17" Porsche wheels that are cheap...

[blueline]

I have no real answer or opinion (and zero experience with Yokohamas), but one thing that I would weigh greatly if it were me would be what and how many tire options are there for the 17" wheels that you could experiment with. Also, what would the cost be for tires for the 17s and how might they perform on AXs vs the Advan A052 tires?

I imagine Willy and others here will have better thoughts on your query.

[Spencan]

From my research so far, almost all of the top performing AX 200 treadwear tires are available for the 17s. Grassroots motorsports did a tire comparison and the Yokohamas were the top tire...

[J-Dub]

What is the estimated cost of options 1 and 2 I guess is what I would consider next.

Option 1 you have the wheels already and tires are approx 1K. What do you think the cost of used 17" wheels in the spec you need plus tires for option 2?

I am liking option 1 so far.

[blueline]

What is the estimated cost of options 1 and 2 I guess is what I would consider next.

Option 1 you have the wheels already and tires are approx 1K. What do you think the cost of used 17" wheels in the spec you need plus tires for option 2?

I am liking option 1 so far.

That's my take too, especially since Spencan's research seems to bear out that the Yokohamas perform very well for AX.

[Spencan]

I actually just saw a set of Boxster wheels that I actually use to have on my car for $425 on Ebay. The other cheaper options of tires for the 17s are around $800-$900.

In terms of handling and other important dynamics, is there a marked difference between 16" and 17" setups?

[Tom]

Porsche published a Technical Service Bulletin about using larger wheels on the 944. I can dig it up this weekend, but if I recall correctly, the gist was to use 968 castor blocks if you use 17" rims, and not to use 18". The 18" wheels stress out ball joint on the track. I'm not a big suspension expert, so others might correct me on the details, but suffice to say Porsche had opinions on the subject.

[Spencan]

18s are not an option. 16s or 17s are what I am trying to decide between.