Assuming the PPI is clean. I will be picking up a 2000 Boxster S this week.
This car will be primarily a track and AX car. Some street. The unit has 18" Turbo Twists now. These will be used for street tires.
I want additional wheels for track tires. Should I go with 18s or are 17s just as good? I think wheels and tires are less expensive in 17". Thoughts? Experiences?

TIA

 

If I were not competing with the car in a restrictive class (i.e. just doing lapping days) I would by all means go with 17's. They are much cheaper, easier to find, lighter (in general) and give you almost as many options as running 18's. There are bunches of good sticky R-compound tires in Boxster-friendly 17" sizes.

 

I find the MPSC are about 15% less in 17s.

What size Hoosier A & Rs will fit these cars? I don't see any 255/40/17 or 265/35/18 Hoosier Rs at Tire Rack. Am I missing something or do you use other sizes?

 

For AX, I know folks have run 245s all around on the Boxster. Helps dial out some understeer. I think the next size up is 275s. Yes, no 255 or 265 Hoosiers.

If you are on a budget, 17's (the rims - about $700 used, give or take) and 17's (the tires) will be cheaper. I have 18's on my Boxster and I was unpleasantly suprised to learn my 18" Toyo RA-1s were a little over $1,000 (and that didn't include mounting). My old car (a 911) with 16" rims, tires cost about $700/set (still under 800 mounted).