19" Alternate tire size

[voodoocat]

Hi, I think some people 'size up' from stock, but is there any problem going down in size?

The Porsche 19" wheel is 9.5 x 19 (275/45/19 stock), so fit to the wheel is ok, with slight speed difference. But is there a problem with fitting these tires on 04TT? I don't have TPMS. Thanks!

[Faceman]

If it mounts up you may notice a small difference in the comfort of your ride -driving over bumps and maybe cornering a bit. Passengers probably wont notice it but I feel almost everything after Ive had a car for a while.

Also, it doesnt snow where I am and it hardly rains. That could be a big deal.

[flintworks]

Why do you want to go down a size? A narrower tire will give you less grip, less resistance to hydroplaning, etc. Also keep in mind changing the tire size will throw off your distance to empty reading and put miles on the odometer faster.

[odix]

One reason -- narrow tires excel in the snow. More weight focussed on a narrow rolling point equates to better snow/slush/mud traction compared to a wide tire with diffused weight over a broad area, that's a troublesome set-up in the snow.

The Porsche spec notes tires as narrow as 235mm acceptable for Cayenne (235/60 R 18).

And you can select your tire set-up via the on-board computer (this may be for tire pressure monitoring option only)

Attached from the '04 owner's manual.

Edited July 14, 2010 by odix