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Cayman Tires & WheelsDiscussion of Tires, Wheels, Suspension, etc.
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I'm ready to order a set of Dunlop Z1 star specs from TR and got the question from the salesperson of whether the 275/35/18 will fit in place of the 265/40/18.
I looked at the wheel well and there appeared to be sufficient room for the extra .3" of tire section width but who knows.
I'm guessing there are dozens of people using this width on stock rims without rolled fender lips on this board, but would appreciate hearing that this tire size has been used ont he cayman successfully--thanks for any help.
I'm ready to order a set of Dunlop Z1 star specs from TR and got the question from the salesperson of whether the 275/35/18 will fit in place of the 265/40/18.
I looked at the wheel well and there appeared to be sufficient room for the extra .3" of tire section width but who knows.
I'm guessing there are dozens of people using this width on stock rims without rolled fender lips on this board, but would appreciate hearing that this tire size has been used ont he cayman successfully--thanks for any help.
You can do this but would have to get 245/40/18 for the front or risk more understeer. I was at a track day last weekend and somebody recommended those tires. I personally am going try the Falken 615's in those sizes as soon as I burn through my latest set of PS2's.
gmorat:
Thanks for the reply. I looked at the 245/40 but the spec sheet on the tire--if the numbers were accurate--had the OD slightly bigger than the 275-35, which would be on the rear. I'd like to keep the rear a bit larger than the front, even if it's just by .5"
I looked at the wheel well and from I can see the the extra .3" width should work; from some of the earlier threads, this is a pretty common size used on Boxsters and Caymans.
Stock is 235/40/18 on the front and 265/40/18 for the rear. The rears are the ones that are an odd size as 265/35/18 is much more common. As soon as you say your not going to use a stock rear size a whole world of possibilities becomes available. Whats the full name for the Dunlop Z1's? also has anybody used them yet on a CS?
FYI. The circumference of the tire and therefore the revolutions of the wheel are different. Is the Cayman speedo/odomerter sensor on the rear or front? If on the rear your speedo with read 2.9% faster than accurate.
Also since all wheels have ABS and PSM senors, both PSM and ABS function will be affected to a certain degree.
While it can’t overcome the laws of physics, the revolutionary Porsche Stability Management (PSM) system does lend an added degree of balance and control to the Cayman’s mid-engine driving dynamics, inspiring surefooted confidence in corners and extreme situations.
A standard feature on the Cayman and Cayman S, PSM continuously monitors steering input, road speed, yaw velocity and lateral acceleration to calculate the actual direction of travel. If the car begins to steer off line, PSM instantly intervenes with precision brake inputs on individual wheels to help bring the car back onto the driver’s intended path.
If braking alone isn’t enough to correct the vehicle’s cornering line, PSM then calls on the Cayman’s engine management system, adjusting engine output as needed to help stabilize handling. PSM can also compensate in an instant for mid-corner changes in load resulting from deceleration or braking. When Sport mode is selected with the optional Sport Chrono Package, PSM’s threshold for intervention is raised, allowing for greater driver involvement. If you prefer driving without automatic PSM assistance, the system can be set to standby at any time. In this case, it will only intervene under heavy braking, where both front wheels exceed the ABS threshold.
For all of its technical ability, PSM goes virtually unnoticed in everyday driving situations, preserving the Cayman’s natural agility.
I'm ready to order a set of Dunlop Z1 star specs from TR and got the question from the salesperson of whether the 275/35/18 will fit in place of the 265/40/18.
I looked at the wheel well and there appeared to be sufficient room for the extra .3" of tire section width but who knows.
I'm guessing there are dozens of people using this width on stock rims without rolled fender lips on this board, but would appreciate hearing that this tire size has been used ont he cayman successfully--thanks for any help.
275/35/18 will fit but the overall diameter is slightly less than stock 265/40/18. I chose 275/40/18 and 245/40/18 for track tires (Toyo R888) and they fit fine. 275/40/18 is just a hair taller than stock and width is fine with stock rims.
I had a set of 275/35-18 tires on my rear wheels. One cosmetic thing you might not like is that it leaves a noticeably larger "gap" between the tire and the fender (unless your car is lowered). You might not like that look. It's a minor thing, but you don't want your rear wheel/tire combo looking too small (diameter-wise) for the wheel-arch.
Another thing. Given nearly equal widths, the drop in aspect ratio from 40% to 35% results in a shorter sidewall which may slightly increase ride harshness. More importantly, it has the effect of slight increasing your rear cumulative spring rate. Unless you make a matching change at the front, the balance (front to rear) of the spring rates will be altered. Stiffer in the rear will tend to reduce understeer and increase oversteer (at the limit only of course).
Like I said, I ran with this set up for a year on my track tires, and it was fine. But when I swtiched to new track tires, I went back to stock sizes and the car was slightly less oversteery....more stable in fast corners, plus a bit more understeer to contend with in slow corners.... (and I went faster with the new tires, but that might be because of other things).
These are minor differences I am talking about. Just food for thought.
-Q
I'm running 285/30/ZR18 on the rear with -2.1 camber and lowered ~ 1.25", so you will have no problem with your tires. I want to find out if 18" wheels with 9.5" rims and 265/35/ZR18 will work in the front without clearance problems with fenders or suspension (spacers are OK).
Until 
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