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Cayman Tires & WheelsDiscussion of Tires, Wheels, Suspension, etc.
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My Boxster came with Boxster S 18" wheels
235/40/18 fronts and 265/40/18 rears
What happens (Pros and cons) if I put 245/40/18 fronts and 275/40/18 rears?
Will the PSM be affected? car will have worse handling or better?
Will the tires fit the rims? Any risks?
PSM - Porsche Stability Management
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'd like to know for sure also. But I'll stick my neck out by speculating that the extra 10mm won't make much difference. Then I'll wait to hear otherwise from someone who's mounted the 245/275 sizes.
Tire Rack sells Michelin PS2s in all the sizes you mentioned. Their spec sheet shows very few differences between the two front sizes and the two rear sizes.
Both front sizes will fit on an 8" rim (both better on a 8.5" rim though); the 245 weighs 2# more, and is .3" taller.
Similar for the two rear sizes. Both will fit on a 9" rim (both better on a 9.5" rim though); the 265 and 275 weigh the same (27#), and the 275 is .3" taller.
I don't think the .3" differences in diameters will cause a PSM problem, as the OEM diameter stagger front to rear remains the same. But only the OEM 235/265 sizes come Porsche N-rated.
I have the 8 and 9" rims and never considered using the wider sizes. But the 245/275 sizes should work better on 8.5 and 10" rims.
PSM - Porsche Stability Management
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.
Tire Rack
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You will be fine. I have that setup on 19" wheels. You will not trip ABS or PSM.
As for handling, that's subjective... I would say that unless you are auto-X'ing or tracking the car often, you won't feel much of a difference on a day-to-day basis.
If anything, those sizes will make the tire look a bit 'meatier' on the wheel, if that matters to you.
PSM - Porsche Stability Management
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've done this on my 18" CS wheels, but not with normal street tires, so I cannot render a true apples-to-apples comparison for you. I mounted 245/40s on the fronts and 275/35's on the rears (stock 18" CS wheels, Toyo Proxes RA-1 tires) and they fit fine, and handled fine to/from/on the track... no rubbing, rollover, ABS or PSM problems.
Generally, wider tires will be a bit noisier (assuming same model tire). And at these modest +10mm widths, you are still within the allowable tire widths that can be safely mounted on the stock 8" wide front & 9" wide rear wheels.
But it's debatable whether the extra 10mm will provide any noticable benefit when mounted on your stock wheels because what you gain in tread-width you lose in sidewall spread. Maybe you'll end up with a tad more lateral and braking grip in dry conditions, and fractionally more sidewall flex. Collectively it won't amount to any earth-shattering improvement. If all you are doing is street-driving, I wouldn't put this too high on your priority list of mods, but it will work if the tires you crave only come in those sizes.
Just my $0.02
Q
PSM - Porsche Stability Management
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 running 245 and 285 now with custom wheels - plan on going 255 and 295 for my next set. Lowered w/ KW coilovers and no issues at all except had to trim the debris deflectors on botton of the fender liners over an inch.
I'm running 245 and 285 now with custom wheels - plan on going 255 and 295 for my next set. Lowered w/ KW coilovers and no issues at all except had to trim the debris deflectors on botton of the fender liners over an inch.
DesertCaymanS;
Would you mind posting some pictures of your car? it is one of the most beautiful White CS's I had seen, and makes me proud to have a white one myself..!
Gilles
I'm running 245 and 285 now with custom wheels - plan on going 255 and 295 for my next set. Lowered w/ KW coilovers and no issues at all except had to trim the debris deflectors on botton of the fender liners over an inch.
Hi, Could you please post some picts of the trimming you had to do to get the 255's to fit on the front...
Thanks!!!
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