Max tire size on 9x18 rear wheel

[KRAM36]

Originally Posted by BYprodriver

Loss of torque multiplication is the unavoidable downside of running taller than spec rear tires. This is very noticeable on 986's. That leaves a 285/30/18 as the only option along with 10" X 18" wheels. Now the car resists rotating into turns!

I'm not following you on this one.

Here is what my car originally came with.



This is what I'm moving to.



Not only is the tire diameter smaller the front to rear tire rotation speed is much much better. The car should handle much better.


.

[PaulDash]

Please please please send me photos of your car after you fit these on. I'm looking to buy the same.

[woodsman]

Originally Posted by KRAM36

I'm not following you on this one.

Here is what my car originally came with.



This is what I'm moving to.



Not only is the tire diameter smaller the front to rear tire rotation speed is much much better. The car should handle much better.
.

Your car came with 265/35/...not 40 series

I also look at tire weight. I'd run 255/35/18 since it decreases overall dia, and weight and will provide me with enough lateral grip.
Tire choice within the mfg's range also determines how the tire performs because it affects the shape of the contact patch ie. how fast it breaks away in various directions. These ultra -low profile tires offer the sharpest response at the expense of a gentle breakaway and the widest 'approved' choice will provide the most lateral grip at the expense of a gentle breakaway to wheelspin and a locked tire.

[KRAM36]

Your right. I was going off this guys listing since my wheels got swiped before I purchased the car.

http://986forum.com/forums/boxster-parts-sale-wanted/54450-fs-porsche-boxster-18-carrera-light-ps2.html.

Fronts are 18 x 7.5 ET50 (PN: 996.362.138.00), tires 225/40/18
Rears are 18 x 9 ET52 (PN: 996.362.134.05), 265/40/18

Always made me wonder why Porsche ran those size tires?

2003 Porsche Boxster Options & Packages Prices - Motor Trend Magazine

18" Light Alloy Carrera Wheel - $2,920
Front alloy wheels with 18 inch rim diam and 7.5 inch rim width , rear alloy wheels with 18 inch rim diam and 9.0 inch rim width; Front tires with 225 mm tire width, 40% tire profile and Z tire rating , rear tires with 265 mm tire width, 35% tire profile and Z tire rating; External dimensions: front track (inches): 57.7 and rear track (inches): 59.2

Anyways, with the 265/35 series the 275 is only 1.1% more in circumference size. Doubt one could tell the difference from seat of the pants and get the speedo closer to the actual speed of the car lol.

[woodsman]

1.1% the wrong way--decrease in overall gearing and increase in weight. 255 is win/win but no doubt 275 looks better. I ran 225 all the way around for 4 months and the only real difference was looks and the car was noticeably quicker. I think the 's' is overtired from the factory in order to keep people on the roads including the degree of stagger front to back. Sometimes less is more but no doubt bigger looks better.

[KRAM36]

Originally Posted by woodsman

1.1% the wrong way--decrease in overall gearing and increase in weight. 255 is win/win but no doubt 275 looks better. I ran 225 all the way around for 4 months and the only real difference was looks and the car was noticeably quicker. I think the 's' is overtired from the factory in order to keep people on the roads including the degree of stagger front to back. Sometimes less is more but no doubt bigger looks better.

Like I said 1.1% your not going to notice and since this is a daily driver it could offset the weight with lower RPM's and better gas mileage during my commute to work, which is 90% highway.

My car has 255's on the rear for the summer and there's just not enough grip for me. The rear end comes out too many times running my favorite twisties with those tires, which are Dunlop Direzza DZ101. I'm going with Michelin Pilot Super Sport tires and lighter OZ Alleggerita HLTwheels, think I'll be just fine with that combo.

[stephen wilson]

Originally Posted by woodsman

1.1% the wrong way--decrease in overall gearing and increase in weight. 255 is win/win but no doubt 275 looks better. I ran 225 all the way around for 4 months and the only real difference was looks and the car was noticeably quicker. I think the 's' is overtired from the factory in order to keep people on the roads including the degree of stagger front to back. Sometimes less is more but no doubt bigger looks better.

If you didn't notice a difference in cornering capability with 225's, you're not driving hard enough to care. I could feel the difference in balance just going up 10 mm on the fronts. Wider tires will benefit cornering grip, with a minor detriment to acceleration.