Hi,
I just bought a 08 Boxster S and it came with 19" Carrera S (lobster forks) wheels. My question is this; has anyone traded up from 18" to 19" or traded down to 18" wheels on a Boxster or Cayman. I've heard that the 18" rides significantly better than 19" and I've heard that 19" offers slightly better handling but not enough to offset the improvement in ride. BTW, I also have a 911 with PASM and I think 19" ride fine but the Boxster S has standard suspension. Any feedback is appreciated.

 

General consensus is that 18" with a 40 series profile does ride more compliant than 19" with 35 profile. After all, you're riding on more rubber/air. If you were to take a poll amongst Boxster/Cayman owners, you'll likely find majority of them say 18" wheels offer better ride (less harsh and jarring). You'll also find folks who say 19" wheels ride just fine. Then again, a lot of that has to do with where you live. Down here in S. FL... most roads are free off pot holes and 1" wide expansion joints like up north. So, it's not a big deal. On the other hand, if I were to live in Boston still.... I'll probably stick with 18" to (1) have a more compliant ride, esp long trips on the highway, and (2) minimize bending wheels from pot holes and what not. HTH.

 

Specification Sidewall Radius Diameter Circumference Revolutions Speedometer Odometer Difference
265/35-18 3.7" 12.7" 25.3" 79.5" 797/mi 60MPH 10000mi N/A
275/30-19 3.2" 12.7" 25.5" 80.1" 791/mi 60MPH 9924mi 0.8%

This conversion is based on my vehicle. As you can see, the actual difference in tire thickness or profile is negligible. However, the difference between the oem wheels and the after market ones with regard to unsprung weight and rotational mass is significant. Probably close to 50 lbs.

 

Thanks for the input, I've been looking into wheels and the 18" replica wheels are about 4 lbs heavier than OEM, do you think that's a big issue?

Bob

 

I think its fair to say, for the most part the members of this forum are performance conscience enthusiasts. With that in mind, one of the first steps at improving performance is upgrading to a lighter wheelset, thus reducing unsprung weight and rotational mass. In my experience, the majority of high end wheel manufactures have focused their efforts on designing wheel applications for Porsches that begin with a19 inch diameter.

 

understood, I have HRE P40's on my 997 Turbo but was looking for an upgrade wheel/tire set up for the 987 that was a bit softer than 19" wheels, that's why I was thinking about the 18" set up.

 

FWIW, on the Boxster (987) the 18 inch wheels feel a lot better than the 19", I had some Carrera Classics in 19" that I originall purchased for my 06 Boxster S, even with PASM the ride was harsher than the 18", you could also feel a bit more cowl shake with the 19" as well. So I ended up just driving the car with the OEM 18"s while owning the car.

 

I have a 987 with the 19inch lobsters. Your first summation of tire sizes and performance is about right.

However, going with a 4lb heavier wheel in the smaller sizes will give a better ride, but worse performance because of the weight.

I suggest looking further, for an 18" wheel set, that doesn't weigh more than stock. Keep in mind replacement tires vary in weight by up to 4 lbs as well.

 

Thanks for your feedback, I will continue to look for OEM 18". The prices are pretty high for new wheels from reputible places although 18" replicas are plentiful on ebay at around the $800 a set price range vs. oem at around 3k a set.

 

another option is to get refinished stock wheels from someplace like finishline wheels or lakeshore wheel and tire. both are located in Michigan and sell factory wheels that have been refinished (road rash, slightly bent, etc...) they look new and guaranteed to perform as new once refinished. Should be able to pick up the stock boxster S 18" for around $900ish... try finishlinewheels.com or lakeshorewheelandtire.com

 

You should be able to find a set of 18" take-offs from a cayman or boxster on the various Porsche forms easily. They usually go for ~$800 without tires and no more than 1200 with tires and 60-70%+ treads. With so many people upgrading to aftermarket wheels, just keep an eye out for them.
I'd sell you mine 18" Boxster wheels with PS's (5k miles), but I'm thinking of keeping them (wheels+tires) for DEs. 19" tires are expensive and I just don't want to thresh them around.

 

Thanks for the feedback!

 

I've seen their web site, also a consideration, thanks for the info.

Bob

 

OEM 18 inch wheel/tire set combo:

http://www.planet-9.com/classifieds/...-3b-tires.html

BTW: Looks like a new member of planet-9 so caveat emptor.

 

Thanks- understood