987 Boxster 18" Wheel Questions

[vincesf]

Recently, I found a set of new OEM 18" Boxster S wheels. I currently have new 19" wheels on my car and instead of replacing the tires, I thought I would replace them with 18" wheels and store the 19" wheels. My questions are:
1. What is the recommended tire pressure (front and rear) for the 18" wheels/tires?
2. Are the tire pressure sensors interchangeable, so that I can remove them from my existing 19" wheels and install them in the 18" wheels.
Thanks,
Vince

[husker boxster]

Hi Vince,

Let's start with Q#2 first. The sensors are probably interchangable but your better option is to buy a set from Tire Rack or your favorite discount Porsche dealer (Suncoast or Sunset). You can get a set for just over $400. Then you don't have to worry about a tire tech messing one up trying to pry it out of one of your 19s.

Now for Q#1. I have my 18" snows mounted on a set of Cayman wheels. I put sensors in them. When you put them on, the TPMS asks you if you've got 18s or 19s. When you enter 18, it tells you what the pressures should be for 18s (26F / 33R).

[eslai]

I believe you will find a sticker on the car when you open your door that tells you what the pressures should be for the entire range of offerings from Porsche.

By the way, I still have a set of 18" 987 wheels if anyone is interested.

[Savanh]

Will those fit 99 boxster? Thanks!

[vincesf]

[QUOTE=eslai]I believe you will find a sticker on the car when you open your door that tells you what the pressures should be for the entire range of offerings from Porsche.

On my 2008 987S, the sticker only refers to 19" wheels, as that was the original equipment on my car. I contacted the dealership to purchase a replacement door sticker, reflecting 18" wheels, and was quoted $235.00 for the sticker! Apparently, the sticker needs to be very specific as to the serial number of the car, etc. I think I shall pass on that one, and I appreciate the information from Husker Boxster, providing me with the correct tire pressure for 18" 987S wheels/tires, at 26 lbs front, 33 lbs rear.

Vince

[roadracer311]

I run my 18's at about 29/36 lbs. They seem to wear more evenly. At the recommended (lower) pressure, they were getting the classic under-inflation wear pattern (it was subtle, but enough that it shortened the useful life of the tires by about 10%)

On long trips (I've done a couple 1,000 mile round trips to Oregon) I've run them as high as 32/38. I got 29.8 mpg on the way up, and 28.8 mpg on the way back with the AC on :-)

Your car looks great! (I'm pretty sure I've seen it around the Richmond district)

[eslai]

Originally Posted by vincesf

On my 2008 987S, the sticker only refers to 19" wheels, as that was the original equipment on my car. I contacted the dealership to purchase a replacement door sticker, reflecting 18" wheels, and was quoted $235.00 for the sticker! Apparently, the sticker needs to be very specific as to the serial number of the car, etc.

WOW seriously!? I can't believe they would have a different sticker! Mine shows the pressures for 18" and 19", although mine came with 18's. That's just ridiculous! And the price for a replacement is damned nutty!

Savanh: They will fit, and here's my for-sale thread if you want more info.

[husker boxster]

The sticker in my door also only refers to 19" wheels.

I wondered if the TPMS would send a warning if it thought you'd overinflated the tires but a quick check of the owners manual says it wouldn't. It only sends a signal if your tire is low (3-6 psi below recommended) or if it detects a tire is flat. So adding extra air wouldn't bother it.

BTW...
Why don't you want to keep the 19s on? They look great on your car.