For winter storage, I would like to install some cheap tires from a junkyard to prevent flat spotting my run flats. Anyone have specific bolt circle diameters for C5's and what other cars would use this pattern. Any chance different tire diameters could damage the ABS/Active Handling System?

 

Well, as long as the car is in storage the diameter is
not going to affect ABS/AHS systems. Perhaps you
are thinking about driving to the storage spot with the
temporary wheels - I'll leave this case to someone
with better knowledge.

The C5 shares a bolt circle dia with many other GM's
that also have the same 5x120.65 (5x4-3/4") pattern.

Your issue is going to be finding a wheel with enough
clearance to fit over the calipers, I believe. I don't
know how economic four would be but as this pic shows,
the spare wheel from the GTO fits the C5

The A-Mold wheel used on C4s is said to fit but the
earlier 17 x 9-1/2 wheels from 88 up do not.

As far as the bolt pattern goes, here is some
5x120.65mm cross-reference info I came across:

Bolt Pattern_____Thread___ Center Bore
5x120.65 mm___12x1.5____70.5 mm

CHEVROLET
Camaro '82-92 5x120.65
Camaro '93+ 5x120.65
Corvette C4 5x120.65
Corvette C5/Z06 5x120.65
Corvette C5 50th Anniv. 5x120.65
Blazer 5x120.65

GMC
Jimmy 5x120.65

JAGUAR
XJ 5x120.65
XJS 5x120.65

LAND ROVER
Discovery V8 5x120.65

PONTIAC
Firebird '82-92 5x120.65
Firebird '93+ 5x120.65

** ---- Also ----- **

Buick - Regal, Century, Special (most mid-size) '64-'80's
Chevy van
Chevrolet - all (exc. as noted elsewhere) '49-'89
Corvette all
Corvair '65-'69 5-bolt
GM compact and midsize
Oldsmobile - 442, Cutlass, F-85, Toronado
(most mid-size) '60's-'80's
Pontiac - GTO, LeMans, Firebird, Grand Prix
(mid size) '64-'80's

 

Note that the centre bore is also a consideration.

I would say that if you found a wheel with the right
pattern and it fit over the caliper but it had a bore
larger than the C5, I would park the car on it
but I would not drive the car on it.

Others may post that it is fine to drive on a wheel
that is not a hub-centric fit. If they do, then you'll
need to make your own decision about this.

.

 

Why not just pick up a set of wagon wheels from the C5 parts for sale...about a hundred to hundred twenty five dollars, put some cheap used tires on it and save them for storage only.
hth

 

Actually there have been some good and long discussions on the topic of flatspotting of tires here on the Forum lately. Do a search and you'll probably find some interesting comments and suggestions.

The bottom line is that you would probably have to park your car for years to flatspot modern radials. I parked an '85 Corvette on the original Goodyears for 9 years and the hardness of the tires was much more of a factor that was flatspotting... although they did feel flatspotted until thoroughly warmed up.

On the otherhand if you just gotta do it... I concur wagon wheels can be had for next to nothing and you know they'll fit.

Good luck... GUSTO