DeWolf

Hi All,

Will 17 x 8 ET49 front and 17 x 9.5 ET52 rear fit my 1986.5? Apparantly made by BBS for the 928, apparantly.

Thanks in advance.

Scott

MjRocket

In my opinion that front offset is to low, you will most likely get a lot of trameling.

Hilton

Scott, your '86 has the S4 suspension (all non-USA 86's do), so the lowest practical offset is ET55 (which on the late suspension, eliminates all the the stability provided by negative scrub radius from the suspension). Less than 55mm offset and the car needs to be steered to stay pointing the way you want it to - if you're driving straight, it will try to not point straight (by following every bump and camber in the road - i.e. tramlining).

For 78-85 (and early '86 in the USA), they can get away with as low as ET50.

GlenL

Fit? Yes. Although the low offset will reduce the diameter of tire that'll fit in the wheel well.

Work well? No.

DeWolf

They are 3 peice wheels so I may be able to change the offset.

Vilhuer

Problem is where to find narrower outer rim. Reason for so bad ET is that enough inwards turned rim do not exist. Changing inside rim will not help at all.

DeWolf

with the 49 offset front will the wheel extend outside the fender, does anybody know?

Jerry Feather

You can determine this for yourself if you just do the math. Start with what you have on the car now or have most recently had on the car. You may need to put it back on the car to remind yourself about what the wheel/tire-to-fender clearance was. Then you need to learn again just what "offset" means. That is the distance in millimeters that the centerline of the wheel rim is from the face of the wheel mounting surface. Then compare the width of the rim, 8 inches in the case of your hoped-for wheels, to the wheels on you car. If the wheels on your car are 7 inches wide that means that half of the difference will be on the outside, a half inch or about 12 mm.

So, if your original wheels happen to be 49 offset and 7 inches wide, the 8 inch wheels will be a half inch closer to the inside of the fender. If you had a half inch of clearance with your original wheels the 8 inch ones will be right at the fender, which would probably be ok. However you don't likely have 49 offset with your original wheels and either 52 or 65 instead. If the originals are 52 offset that means that the new wheels will be about an eighth inch (3mm) farther out. If you had more than a half inch of clearance with the originals you are probably still ok. However, if you have 65 offset with the original wheels the new wheels will be 16 mm farther out from the originals, on top of the half inch from the wider rims, and it is not likely that you had that much clearance, 12mm plus 16mm, or an inch and an eighth, originally, so the new wheels will likely stick outside the fenders.

See how simple it is to answer you own question?

Jerry Feather

One other consideration is the possible use of a negative spacer. However, there is no such thing. But, if there happen to be spacers there now they might be removed and that would work something like a negative spacer. Then the length of the studs may become an issue.

Fronkenstein

Here are some other good resources:

http://www.alloywheels.com/Tyre_Calculator
http://www.944racing.de/wheelweights.php
http://www.rimsntires.com/specspro.jsp

Fronkenstein

UpFixenDerPorsche

Scott, have BTDT years back. If the front ET is not 60-65mm then it's just not the same car to drive.

One further point: make sure the steering rack bushes are not worn or loose. If they are then U'll have terrible tramlining probs whatever wheels U fit.