Track Wheel Setup - Square vs Staggered

[Brad Roberts]

Something else we have worked very hard on.. changing the track width.

Add rear wheel spacers

(all my cars run screw in pro-style studs, I helped Tarett develop what I feel is the best on the market right now)

If you add spacers up front it makes the scrub worse.. on the rear? game on (I don't run them in spec) but if you need *just* a bit more grip in the rear? start with 5mm spacers.

[steved0x]

Typically you can get plenty of camber on the rear, especially if there is any lowering at all. I am at -1.9 and I am at OEM USA ride height. In fact when you get some lowering, often the camber is excessive and can't be dialed down without adjustable toe links. Another considering in using GT3 LCA shim type arms in the rear is you don't want to mess up the axle geometry, I think that is why some folks have trouble getting enough front negative camber on turbos and C4s, and there are axle spacers from Porsche that help to resolve this.

[mwestboxster]

I'm apologizing in advance if the answer to my question is in here somewhere and I missed it.
I own a Boxster which is a street car and run factory original wheels and tire sizes. I have 2 C5 Vettes, a Z06 for track and conv for street. I have 2 Miata's. Spec set up for track and 1 for street. I run 4 square set ups on all 4 cars. Essentially same tires and wheels except in winter when I go to an all weather tire for the street cars. The 4 square set up simplifies things for me. Rotating tires, moving tires and wheels between cars etc.

I do between 30-40 DE (no autox) track days per season. I run in instructor and advanced groups. My days of of running for times are long gone. I'm out there purely for fun. I'm in the process of negotiating a buy on a '09 Cayman S. The plan for this car is to keep it completely stock, any modifications will be minor and only for better/safer performance such as maybe brakes if necessary. Otherwise, no racing seats, no roll bars, no harnesses no nothing. Keep it as street as possible and will be driving to and from tracks.

My question that I did not see answered here are what would be the best size tire to run on all corners. I did see 255's mentioned for rears but not on all corners. If it makes sense I'd prefer a 17" wheel but would go to 18", would definitely not go to a 19" wheel. On my Vette I use spacers on front but only for wheels to clear bigger calipers. I had a v8 Miata and ran 4 square with spacers on all corners to clear bigger calipers.
Summing up:
What size wheels would work best?
What size tires on all 4 corners would work best and does it make sense to go wider then 255's?
I think that's about it.
Thanks

[steved0x]

In Cayman sizes (roughly 25.5-.6" diameter) there are hardly any tires that fit on the Cayman 17" wheels, 245/45/17 is one and 275/40/17 but the 275 is too wide for the oem wheel and barely anybody makes wider 17" wheels for Porsche fitments unless they are $$$. However plenty of good 18" wheels and lots of tires in those diameters. You could run 225/45/17 and 245/45/17?

On 986 Boxsters i have seen 255/40/17 square and I think 225/45/17 square on Hoosiers or hankook z214

[JayG]

Originally Posted by steved0x

In Cayman sizes (roughly 25.5-.6" diameter) there are hardly any tires that fit on the Cayman 17" wheels, 245/45/17 is one and 275/40/17 but the 275 is too wide for the oem wheel and barely anybody makes wider 17" wheels for Porsche fitments unless they are $$$. However plenty of good 18" wheels and lots of tires in those diameters. You could run 225/45/17 and 245/45/17?

On 986 Boxsters i have seen 255/40/17 square and I think 225/45/17 square on Hoosiers or hankook z214

on stock 986 17's, you can easily run 255/40-17 rear and 225/45-17 front
those sizes are virtually the same diameter and lot sof tire choices in those sizes

[steved0x]

Originally Posted by JayG

on stock 986 17's, you can easily run 255/40-17 rear and 225/45-17 front
those sizes are virtually the same diameter and lot sof tire choices in those sizes

I did see a Cayman at Roebling one time running 17" Boxster wheels with our sizes and it seemed to work for him. I guess 1/2" isn't that much of a difference, and it didn't look to bad either

[mwestboxster]

Originally Posted by steved0x

I did see a Cayman at Roebling one time running 17" Boxster wheels with our sizes and it seemed to work for him. I guess 1/2" isn't that much of a difference, and it didn't look to bad either

My offer on the '09 Cayman was accepted. It's in Fl and I'm in NJ.
I've decided to fly there and drive the car back to NJ. Turns out it's got stock tire set up on 19" wheels not the 18's I thought. 235x35x19/265x35x19. These are worn summer tires. I'll be ordering tires from TR have them delivered to Fl and mounted before I get there. I've been searching around some other forums and as a result decided to skip the 4 square set up for the street tires. It's too much of a hassle trying to figure out what tires will fit where and on what rims. I've got a short window before heading to Fl to pick up the car, so simplest thing to do is go with what the Porsche engineers decided works best on the car.
Still have a few months before track season starts in the NE and that will give me time to investigate track tire set ups.
Thanks for chiming in.
Next time you hear from me I'll be the proud owner of a Cayman S and a Boxster.

[mwestboxster]

Originally Posted by steved0x

In Cayman sizes (roughly 25.5-.6" diameter) there are hardly any tires that fit on the Cayman 17" wheels, 245/45/17 is one and 275/40/17 but the 275 is too wide for the oem wheel and barely anybody makes wider 17" wheels for Porsche fitments unless they are $$$. However plenty of good 18" wheels and lots of tires in those diameters. You could run 225/45/17 and 245/45/17?

On 986 Boxsters i have seen 255/40/17 square and I think 225/45/17 square on Hoosiers or hankook z214

Steved0x
Thanks for responding. Going with 18" wheels is no problem. I'd like to get as much tread to the ground that makes sense: It looks like from what I see posted that 255's work. Will a wider tread work/fit or is that sort of a diminishing return by possibly adding too much weight & resistance.