Mongo

Okay, let me be clear that I HATE 20" wheels on any car with the look of rubber bands as tires, but these wheels are really nice.

Do they fit on 928s though without breaking anything?

Front: 20x9.5, et 65
Rear: 20x11, et 68

mark kibort

can you measure the backspacing

20s only look bad when the rubber is too low of a profile... but then you get a real tall tire which might not fit. as long as the total diameter is less than 26 in the rear and 25 to 25.5 up front, you are good to go

76FJ55

What size tires are you looking to try to run on those?

The Forgotten On

The front offset is ideal. Not sure about the rear, someone who knows more can answer that one.

This issue with going above an 18 is that the tires have to be thin to fit. I really like the look of the RS rims too and if they would fit with decent sidewalls on the tires I would love to use them.

BBS does make rims with a similar spoke style in a smaller size which might be more appropriate for the 928's suspension to handle.

MainePorsche

They're nice looking wheels, but you really got to have some rubber on them. 20's are excessive IMHO.

mark kibort

front is ok???? (ideal?) 9.5 up front has to have a backspacing of 8" to be "ideal". i think that works out to an offset of about 82.55mm . right now, that front rim is about 1" too far outside the fender. 82.5 - 62mm= 20mm (or about 1") the rear is ideal though if you use a 275 or 295....
63mm is ideal offset for the rear. (also 8" backspacing for an 11" rim) . so that 68 offset rear is only .25" off ideal so it should be fine .

where did you get the idea that a 9.5 with 63mm offset will work for the front?

The Forgotten On

What I meant is a 65 et offset is ideal. Not the width of the rim. I would use an 8 inch wide one up front to reduce the possibility of rubbing.

mark kibort

well, its ideal for a certain rim.... if you just use the max backspacing with a 9.5" rim, you can calculate the offset. Ive pushed the limits with 9.5 and 10" rims up front, right up to the point where i had to pull the fenders out. 9.5" ends up with 8" backspacing and 82mm backspacing. 10s use 8.5" backspacing and then you can use 305s up front!

Nicole

Even if they fit, it doesn't mean it's a good idea.

Remember, the body and suspension of the 928 - the very structure that has to hold up to the road forces - was originally designed with 16" wheels in mind. Not even the GTS got any structural reinforcements going to 17".

Now you want to put 18, 19 and even 20" wheels on your car. The suspension, body and its connections has to withstand forces that can be substantially higher than what these components are designed for.

This may work for occasional drives, but it will wear your car substantially over the long run. You'll end up with a car that flexes more and more, handles worse, and rattles and squeaks.

I've had many discussions about this with a friend who is an Engineer for chassis and suspension at Porsche. He always told me not to overdo it, unless I want to turn my 928 into a worn out rattle trap. He kept emphasizing that some forces multiply with less rubber, and in older cars not designed for it, this can even become a safety issue.

Jim Devine

20's are probably not a good idea. For driving on our fine California roads you want a fairly tall sidewall to compensate for the potholes. A friend had an S 600 Benz with 20's & got to buy 2 wheels due to hitting a pothole at night. Sidewall was too short to act as a shock absorber.

jheis

You'd have to run them without tires to be anywhere close to the correct diameter....

Fabio421

In my opinion, 18's are the biggest wheel that you can fit on a 928 and still have a decent amount of rubber while keeping the total diameter almost stock.

hacker-pschorr

I'm in the no vote as well.

On top of what everyone else has said, your brakes will look ridiculously tiny.

John Veninger

My old forglines were 17x 9.5" wide w/ 73mm offset. Running 275's. That filled the entire wheel well on the GT and fir perfect.
I would not use anything bigger that 18's on a 928.
Porsche does not recommend anything beyond 17"

mark kibort

thats .4" wider than the 82mm offset i recommend.. certainly fine for the 275s no problem here. tough for 305s though..thats where the greater offset pays dividends.

dont get too crazy and analyitical here.. there are far more forces going on that stress the chassis than a shorter rubber sidewall . higher pressures can have more effect, and in the end, too much sidewall stifness from tire brand or over pressure only makes the car hold the road less (less grip, less force)
so, even though your engineer friend gave a quick pass analysis.... if he really digs deep, there is no issues with going with a 18 or 19" rim even though the cement heads of porsche put 225 50 series 16s on the 928....
the car handles best ive ever had with the 18s, and with bigger rims (MUCH BIGGER) the car handles even better and i have had NO structural issues. this is an order of magntude more force than a short sidewall 20" rim would see. less rubber, probably street rubber , and a rolling diameter not much higher than stock. where do you think this increase wear is going to happen? a-arms? wheel bearings? spindles, steering tie rods ends? again, there are no more forces to worry about... a suspension can be tuned to have a similar ride with a harder tire (less side wall) but over all, yes the ride will be compromized over stock.... the aston martin vantage is the same basic car , weight , power , width and height. it comes with 19s and rides fine .

20s will work and look good, but you need to have some rubber width and height on it, so it might be a little taller. the tires in the picture however, look fine. if the tires are 26" tall in the rear and 25 to 25.5 in the front, there will be no issues and it will look updated and ride fine.

i constantly ran back to back with my 17s and 18s and saw no difference in handling on the track with race rubber. i used a couple of PSI less on the 18s because the side wall was shorter.

we are talking 275x40x17s or 275x35x18s and in the rear 305 35s, 315 30s 335 30s .

the stock car had 7" rims..... the car is WELL overbuilt to support .5gs of handling... up to 1g for this car is expected with good tires and decent size rims. the chassis and components can handle it.