These are from a 911. Front wheels are 7j x17 backs are 8.5j x17.
Will they fit my 928 ? At present I have stock manholes on mine 7jx16

 

Hard to guess which 911 wheels you are considering. Turns out that there may be more than a couple different wheel options for 911 cars over the years.

Critical fitment for the front is that they need to have adequate (negative) offset to maintain the steering geometry. Original is 67 or 68mm, minimum is 58mm. Some are using 55mm offset in front and say it's OK.


The earlier 911's use a strut-style front suspension that doesn't allow for much negative offset. The 928 came along, and Porsche's engineers had the opportunity to correct the limitations that come with the struts. The 928 designers learned from other designs available at the time, specifically from the M-B sport sedans that were very stable cruising at autobahn speeds. The higher (negative) offset eliminates upsets in the steering and car stability when road conditions are different from side to side. Might be one side hits a damaged section of pavement, debris, or even a flat tire. With the corrct offset, a suddenly-flat front tire is almost a non-event. The additional drag doesn't cause the car to swerve at all, letting you move safely to the side. As 9negative) offset is lessened, the stabilizing effects of the negative scrub radius are lost. The car is more subject to tramlining on grooved or worn pavement, stability under hard braking is reduced, etc. You can also run into clearance issues.

There's a tire fitment calculator linked from Andrew Olson's signature line. (username: AO) Look for that, and plug in the actual wheel specs and tire sizes you are looking at.

 

They are from a MY 2000 911, 55ET Front, 50 ET rear. Will they fit ? Any adjustments needed ?

 

My thanks to dr Bob for the advice but when i tried to download the tire fitment calculator, the spreadsheet was blank !! I really could use some more help on this. Thanks in sdvance.

 

There are people using these on the 928, with no interference issues. The front offset is just out of the range that I consider good on the 928. The negative scrub radius number is about 10mm, so a -55mm offset puts you a few MM in the wrong direction. You'll sacrifice some on-center stability, and also find the car more willing to tramline (follow grooves or ruts in the road).

Most 911 wheels of that vintage come fitted with 215 section front tires. This makes some sense on the 911 with the engine out in the back, to help balance the tendency towards oversteer. The front-engined 928 needs a little more tire in front to help balance out some understeer, at least 225 and maybe 235 section, to go with the 255 section rears that come on those 9" rear wheels.