Help with wheel sizes!

[Shaun Sumner]

I'm looking for some help and advice!

I'd love to be able to buy a set of genuine 18" Speedlines (as on a 3.6 Turbo), however, with the limited availability and therefore "˜affordability'; I can't see this happening!

I've looked into various "˜replicas' and been overwhelmed with various different rim sizes and offsets!

Does anybody know what size rims I can put on my 1991 Turbo2 (maximum)? Can anyone explain what the "˜ET' offset value is?

 

[Dave Wilkinson]

Shaun,

This subject always seems to open a bag of worms since there are so many choices. One problem which you have already discovered is that Porsche seem to change the wheel offset (the mysterious "ET" number) with cars across the range so it makes it difficult to ensure there is a correct match between wheels and cars.

The 3.3 964 Turbo you have had, as standard 17" wheels - 7J/ET55 at the front and 9J/ET55 on the rear. The 3.6 Turbo had, as you said, the 18" Speedlines which were 8J/ET52 at the front and 10J/ET61 on the rear.

You would probably get away with the front Speedlines but the rears would almost certainly need spacers (7mm - 10mm) for the ET61 wheel to fit without rubbing something.

If you are going for something a little more economical than the Speedlines you need to make sure that the combination of wheel width and offset (as well as tyre size) will fit. Most of the aftermarket offerings are designed for the narrow bodied cars (i.e. 10"/ET47) which may not best suit the wide bodied Turbo.

It may be better to ask specific questions when you have a combination in mind rather than a general question which has a particularly complex answer.

BTW - have a look at http://www.carbibles.com/tyre_bible.html for more information on what the various terms mean.

Regards

Dave