In reply to a message from Doug Dwyer sent Tue 7 Aug 2007:
Lots of advantages/disadvantages to going to a larger-diameter
wheel. Usually, if you go up a rim size, you go down an aspect
ratio number i.e. 16’’ rim/60 series tire, 17’’ rim/50 series, etc.
to keep overall diameter the same. Tread width gets wider too. The
things to think about include (but are not limited to):
Advantages: As Doug pointed out, handling gets ‘sharper’, and
unsprung weight goes down. The shorter tire sidewall helps the most
here, but the lower tire/wheel weight contributes to this also. But
you can easily reach the point of diminishing returns.
Disadvantages: That same shorter/stiffer tire sidewall that
improves handling also doesn’t absorb bumps as well, so the bigger
the rim and/or shorter sidewall, the worse the ride quality will
get. If all you drive is very smooth, well maintained roads, this
may not be an issue, but if road surface quality is poor, you’ll
definitely know it. And tires with very low aspect ratios (45, 40,
35) are much more likely to substain tire/rim damage if you hit
potholes. Saleen put 18’’ rims/40 series tires on one of their
Mustangs some years ago, and had so many reports of tire/rim
failure from their east-coast customers that they recalled the cars
and fitted a 17’’ combo.
You can increase rim size 1’’ usually with no serious change of ride
quality and noticeable improvement in handling, but once you go
beyond that expect some differences.
Another thing to look out for is tire wear; my experience has been
that as the aspect ratio goes down, so does the DOT ‘wear number’.
Even within the same tire ‘line’, the lower ratio tires don’t wear
as well. I’ve seen reductions of up to 50%. So if tire mileage is
important, look at this carefully.
And I would personally NEVER buy a chrome-plated aluminum wheel, as
the plating will fail in wet conditions after 4-5 years (or less)
unless you’re a fanatic about keeping them clean (front AND back).–
The original message included these comments:
Guys have been wanting more rubber on the road for years, and the lower,
stiffer sidewalls often add quite a bit of sharpness to the steering. I can
–
Why?
Yelm Washington, United States
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