Can anyone tell me what is meant by offset? +58 +68 ? Is offset good or bad?

 

Offset is the distance between the hub mounting flange and an imaginary plane through the center of the wheel. Offset is not good or bad per se but you want replacement wheels with offset as close as possible to the stock wheels. Otherwise you get into all kinds of handling/alignment issues. :cheers:

 

If you are going wider, you may need a different offset. In the front, the offset changes so that the inner edge of the wheel doesn't hit anything when the steering hits at the stops. If you have clearance inboard, the offset is changed to keep the outer edge of wider tires at the same spot to avoid the need to "tub" the wheel wells.

 

Where do I find out the stock C5 offsets? :confused:

 

Anywhere you might purchase wheels should have the factory offsets. :)

 

The more offset the more the wheel goes into the car. OEM C5 offset is in that 60 mm range (do not have data here in my office but can give you this evening if you want)
OEM Z06 offset is lower than OEM C5, so wheels come out a bit, plus half of the amount of the 1" wider rim.
Frederik


[Modified by C5 Frederik, 11:13 AM 5/23/2002]

 

C5 Frederik
I've found in an old post that the offset is 54 front 58 rear. Is this correct? I've been looking to buy chrome replicas. There are a number of offsets advertised. One is 58 65 and don't know if this is bad. Seems that the wheels would set in the well a bit.
thanks for the help.


[Modified by jfpilla, 6:06 PM 5/23/2002]

 

IMO the term "offset" should just be used as a qualitative indication of where the mounting face is. When going to wider rims, the important dimension is the back spacing. Too much backspacing will allow the inside of the tire to rub the fenderwell or rear frame rails. To determine if your setup can handle more backspacing, you can simply trial fit wooden shims between the fattest part of the tire and the wheel well. If you've only got 1/2" or less side clearance, then you probably want to maitain the same back spacing to prevent rubbing. If you then want a wider rim with the same back spacing, then the extra width will go to the outside of the wheel and the numerical value of the offset will be different. By knowing how much wider a new rim is, you can measure where the outside of the wheel and tire will be with respect to the outside lip of the fender. For significantly wider rear wheels, the wheel wells have to be "tubbed" or made wider towards the inside. Fortuneately, this can be done with the C5 by moving the inside of the wells. To "tub" a lot of other cars involves cutting and splicing and moving inwards the frame rails. The front wheels present another problem because these wheels turn to steer and clearances need to be checked on the O.D. of the tire as well. The best source of information on wider wheels and tires is places like this forum in which someone cab verify that he has successfully done this change. Think "back spacing"! :yesnod:

 

I'd like to stay with the stock offset. Whatever that is. If I had the 58/65 offset that would narrow the wheebase, from what y'all are saying?

 

Just found stock offset. 56/65 some ads say 58/65.

thanks for the help

 

Absolutely right.
But you can combine both: backspacing is offset plus 1/2 of rim width (plus the rim border thickness, which is not much)
Frederik