Nurburger

A friend of mine has asked me if I'd like to purchase a set of 17" wheels from his boxster as he just changed to 18's - I beleive they are 3-piece. The fronts are 7.5" wide with an offset of 40mm & the rears are 9.0" wide with an offset of 39mm.

I have a 88 951 - would I need to use spacers? If yes, any idea what size??

Any help would be appreciated.

Spidey944

If you do an advanced search for "wheel offset" or "wheel backspace" under the 944 forums. I think clarks garage.com has a section of backspacing as well.

PorscheDude1

Search, sounds like spacers.

Nurburger

I did search, thank you - but the results are all over the place and mostly focus on the difference between early offset & late offset cars.

So, does the 12mm difference between my offset (52mm) and the wheels I'm considering (40mm) mean I need a 12mm spacer, or that they will stick out of the fenders???

JimV8

Check out this place.
http://www.wheeldynamics.net/appguide.html

GodSpeed

Ok here how offest works: Offset is the measurement from the center line of the wheel to the inboard flange of the hub. In your case you have a 52mm positive offset stock. If you get a wheel that has less positive offset or neg offset it will push the wheels out further away from the car. If you get wheels with lots of offset like 80mm the you will need an 18mm spacer (18mm+52mm=80mm) Get it?
Hope that makes sense.
Unfortunatly with your late offset 951, those wheels will probibly not fit correctly, they will just stickout to far. Thats not saying they wont work, it will be a very aggressive fit, but you will need to mount the wheels to be shure.

Hope this helps,
-Dan

GodSpeed

here a good page I use for wheel measurements:

https://www.rsracing.com/tech-wheel.html

philcav7

Besides sticking out beyond the fenders, what are the other risks involved with using wheels with the wrong offset? I would imagine that it could create issues with the studs snapping/shearing, or no?

GodSpeed

When high quality parts are used, this is less of an issue. Dont buy ebay studs and spacers and you should be fine.

using spacers and adapters should not be taken lightly. I recomend the slipon style spacers and longer studs. I used to get all my studs from paragon products. BBS, H&R, and other reputable companies make nice spacers.

You will want to make shure your suspension, bushing, wheelbearings, well really everything, is in good shape too. larger wheels and lower offsets create more stress on these parts than the stock wheels.

Lastly, I have never heard of any studs that were good quality and installed properly, shearing off.

-Dan

V2Rocket

speaking of offset...correct me if I'm wrong but does an S2 have the same offset as a late 951?

GodSpeed

yes

Nurburger

Dan, thank you for the clarification - I just couldn't get my little pea brain around which way the 12mm difference would go...