Shmurzik

I notice, that it’s a Rennlist tradition to ask at least one question about wheels a day.

So, here it goes: I have a 90 S4 with the standard slitty wheels and a set of kind of design 90-like wheels off a non-running ’86 944. Will the 944 wheels fit onto the 928? ‘Cause, frankly, I am not crazy about the stock wheels and don’t have the cash to buy a new set right now. Thank you.

Ed Ruiz

If the offsets on the 944 wheels is much less than 63mm, they probably will not fit properly. YMMV.

Jfrahm

An 86 944 is early offset, so if the wheels fit correctly on the 86 they will have the wrong offset for the 928. However Design 90's are late offset. If they are tucked way in on the 944 (about an inch too far inset) then they are late offset wheels incorrectly fitted to the 944. The wheels should also be marked with the width and offset near the valve stem. Design 90's should be 52mm offset for a 944. You'd want to check the fit carefully, they would probably fit with stock tires but if you went wider you might get some rubbing.

944's went to late (52mm) offset in 1987 from 20-something... 23mm? If the wheels are early offset, they are useless for the 928.

-Joel.

Shmurzik

Okay, I checked... the 944S is actually 1987. Does this change things much?

Jfrahm

Yes, a 1987 944 is a late offset car. Sounds like they will fit OK (if they are 16".) They will sit inboard of the 928 wheels by 10mm, but if your tires are wider by, say, 20-30mm (265's or 275's in the rear)they should look fine and might not even rub.

I'd have no qualms about putting 265s on 8" D90's.

You will want to look at the widths, if these D90's are on a 1987 car they might be take-offs from a 911 and thus 6" fronts and 8" rears. D90's didn;t come standard until 1989 so they are not original on that 944, they could be from anything. The 6" 911 fronts might not be safe with a standard 928 tire width. 944 D90s are 7" front 8" rear, or 9" rear for the rare M030 wheels.

You might also have club sport wheels, from a 1988 944 Turbo S or 928GT. These are forged and have a pattern near the rim:

<a href="http://wheelenhancement.com/clubsport.htm" target="_blank">http://wheelenhancement.com/clubsport.htm</a>

See the little 'parenthesis' marks? If you found some of these, grab them. Great wheels.

These are the standard cast D90's:

<a href="http://wheelenhancement.com/Design.htm" target="_blank">http://wheelenhancement.com/Design.htm</a>

-Joel.

V-Fib

I have the Club Sports from a 944 on the 79, and have no clearance issues. Very nice rims IMHO. They are 16x7.

Anthony Tate
79/928 Silver Metallic

Ed Ruiz

</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica">Originally posted by Jfrahm:
<strong>
I'd have no qualms about putting 265s on 8" D90's.

-Joel.</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">A 245 on an 8" rim is barely acceptable, and a 255 is considered to be a bit too large to be safe. 265's on an 8" rim are WAY too large to fit safely on an 8" rim. The operative word in that last sentence is "SAFELY".

Just because you can do it doesn't mean you should. Imagine a top drawer basketball player wearing shoes that are two sizes too large. I'm sure he can play, but will he be able to make quick direction changes better than if he played in shoes that fit him properly? I doubt it. YMMV.

Jfrahm

Depends on the tire. Some 265's are rated for 7 to 9 inch rims, and 255's on 7" and 8" rims are commonplace. Consider the 225's on the 7" fronts, if this is a conservative fitment then a 255 should fit tolerably well on an 8" rim, and a 265 is only 1cm wider (and with some tires it's no wider at all.) I think that within reason it's safe. A cm of tire width is not a lot, especially when you consider that one company's 245 is another's 255. As long as you stay in the recommended rim range you should be OK.

FWIW, racers I know seem to be in the habit of mounting much wider than stock tires on thier stock rims. If this compromised grip and handling to any great extent I think they would stop.

-Joel.

Jims928s4

AND this is what it looks like !!

Ed Ruiz

a 225 on a 7" rim is considered at the top limit of a safe fit. The same is true for a 245 on an 8" rim.

Read the rule of thumb of 0.85 to 1.0 for wheel to tire ratio in the section on tire/wheel fitment in the DEVEK catalog.

Like I said in an earlier post, "Just because it can be done doesn't mean it should be done".

Consider this: A 928 with tires that correctly fit (within the 0.85 to 1.0 wheel to tire ratio) on their wheels will out-perform a 928 with a wheel to tire ratio outside the 0.85 to 1.0 range. This is particularly apparent in events with lots of corners. YMMV.

Lastly, those racers using oversized tires on their rims may think they're better off, but in fact they are not. Every road-course driver wants more lateral grip, and to get it they will need wider tires. But the optimum way to use wider tires is with them mounted on wider wheels. Those who go up in tire size, but not in wheel size are just trying to save money. They may be saving money, but they are not maximizing the effectiveness of the wider tire. (See my previous message regarding the basketball player analogy.)

Brent 89-GT

Ed is right on this one. I used to run 225's on 7's and 245's on 8's with my 951 on the track. The tires "bulge" a fair amount on those rims and anything larger would likely have reduced grip and made for squirrelly handling. A 265 should really be on a 9" rim.

Shmurzik

Okay, not to seem stupid (who am I kidding...) but here is the car:
<img src="http://www.komkon.org/~bartenev/928/944.jpg" alt=" - " />
and here is the wheel:
<img src="http://www.komkon.org/~bartenev/928/944wheel1.jpg" alt=" - " />
So, thanks to Joel Frahm, I am pretty sure these are Design 90s. The questions are:
Will they fit?
What size tires should I get?
I have a set of brand new 225/50-16 Kumhos and am wondering if they will be usable with these wheels. Thank you all once again

Ed Ruiz

Your 90 S4 originally came with 7.5"x16" front rims with 225/50-16 tires on them. That's the size wheel you should use up front, at a minimum.

Your original rear wheels/tires are/were 9"x16" with 245/45-16 tires. YMMV.

Just because the wheel/tire fits and works well on a 944 doesn't mean it will on a 928. Remember, your 928 weighs several hundred pounds more than a 944.

Porsche increased the size of the front wheel by an inch for the 1989 GT and then only by 1/2 inch in 1990 to 1995. However, it kept the front tire width the same at 225. The main reason they went to a wider fron wheel but kept the tire width the same was for safety and better handling. Putting a smaller wheel will only make the car handle and brake worse - not better. Again, YMMV.

Shmurzik

Ok... in case you couldn't tell I am thoroughly confused by now. The offset on these should be good (or, maybe, a small spacer could be required) and a couple of people here are using them, but then Ed is saying that I need to use a 225/50-16 tire in front, which I was going anyway… <img border="0" alt="[icon501]" title="" src="graemlins/icon501.gif" />

I guess when I get back to Bay Area, I’ll stop by at Devek and bother them some.

Jfrahm

No, a spacer would be for putting 928 wheels on a late offset 944. To add offset to your 944 wheels, you need an 'unspacer' which science is still struggling to invent. Once we invent the unspacer we can put Fuchs on late offset 944's, what a day that will be.

-Joel.