Another thing that is different for USA vs. the rest
of the world. Negative is positive offset and vice versa.
No tires outside the wheelarches or the cops will pull
you over too. As a general rule of thumb here, go for
wheels in the same offset as original and if there's any
space left over, go for a slightly different offset.
There was this popular 300ZX Z32 body kit made in
Germany that had rear wheels that changed the offset
3 inches on each rear wheel. I dont have to tell you
how quickly they had to change wheel bearings and
that the rear springs and shocks were not doing their
job. When adding 3 inches to the inner rims the car
had 13 inch wide rear wheels but much better wheel
bearing life and handling. Another thing is in the front
if the kingpin offset is increased with these low
backspacing wheels. Try braking hard once and find
out how scary that can be. Smaller tire diameter
will also increase the kingpin offset and make the
car to steer in any direction when braking hard.
Wheel offset is not something the car manufacturer
decide on by rolling a dice today. Some older cars
could improve handling and steering response by
changing offset but dont go too far off.
Thomas
Ronnie Day wrote:
> >Offset and backspacing is not the same thing.
> >Offset is positive unless specified negative.
> >Negative offset is not common on wheels today
> >and it would not fit a Roadster without big flares.
>
> Certainly they're not. I've always considered positive offset away from
> the car centerline, negative toward the centerline. Looks to me like
> many, if not most, of the FWD cars today use wheels with a bunch of
> negative offset. I guess they do that to get the centerline of the wheel
> near or on the steering pivot plane. That's one reason the selection of
> wheels for our RWD toys is rapidly disappearing.
>
> Thinking about it, I guess there are instances in which backspacing, too,
> would correctly expressed as a negative number, but I doubt that folks
> that'll do something like that are going to be reading a list like this
> one. There has been a popular trend among some groups called low and
> wide. Wheels are built that actually put most or all of the tire and rim
> outside the body using a super reversed wheel center section. They tend
> use older style 78 or 80 series white wall tires mounted on rim widths
> that are too wide for a given tire width, but I've seen some with low
> aspect ratio tires, too. I shudder when I see one. All-in-all not the
> smartest things to do, individually, much less in combination. How do
> they turn? Very carefully I'd say. Then there's the decidedly
> asymmetrical load on the wheel bearings and the wheel mounting surface.
> Don't know if this has ever appeared in Europe, but it's been made
> illegal in many places here.
>
> FWIW, Ron
>
> Ronnie Day
> ronday@home.com
> Dallas/Ft. Worth
> '71 510 2-dr (Prepared Class Autocrosser)
> '73 510 2-dr (Street Toy)
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