Wheel Offsets

[Brian Dettling <aa821@acorn.net>]

Regarding the 924 7" wheel with 24? negative offset.

Basic stuff, but to understand terms, maybe go to a web site like "the Tire 
rack"s and grock.  24 mm negative offset, 7" wide rim will do what other 
lister posted.  Kinda depends on tire mounted to it.  When you get wide, 
it sometimes is useful to express the geometry in terms of backspacing.  
Offset obviously should change with wheel width.  Stock neg. offset for 
OEM VW 6" wide wheel is usually 38 mm.  When you increase width by 25.4 
mm or 1", half of that or ~ 12mm should come from both sides, hence a 
~25mm neg. offset is kinda OK for 7" wide wheel.  There is another issue 
that may or may not be important to you.  VW designed front strut 
suspension with negative roll radius so that you have some self 
correcting.  IE, if two wheels drop off pavement, car won't lurch to 
outside as much if there wasn't neg. roll radius.  BMWs do the opposite, 
so its not an absolute.  At some wheel width/offset you diminish the neg. 
roll radius.  Exact figure I don't have handy.
A1 VWs like to have 4.5-<5" of backspacing.  More than that and you 
interfere with strut housings.


As regards wheel bearing life:  

All IMO, rear taper bearings are robust enough for different path loads, 
fronts are marginal, but they are that way stock.  My first wheel bearing 
change on 87 `16V at ~40k I repacked new bearings with Redline synthetic 
grease.  Did not make discernible difference is life span.

HTH,
-- Brian D./OH
How can you be in two places at once when you're not anywhere at all...
Firesign Theatre

q

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