<VV> Donut Spare Tire
ed_dowds at hotmail.com
Fri Jul 7 14:07:04 EDT 2006
I have been told that one should not run different size tires on the drive
end of any car, not just ones with a posi. The thinking is that different
size tires will cause the diff to use the spider gears constantly as opposed
to their designed function of allowing the wheels to turn at different
speeds for turns.
A posi is designed to limit this action so the stress would be worse for
them with different size tires.
The spider gears in a Corvair diff are not that great to begin with so
exposing them to additional stress is not a good idea.
As was mentioned you should use a donut on the drive end ONLY if it is the
same diameter as your regular tire.
Most owners manuals for cars that came with donut spares say to only use it
for 50 miles. I suspect that they want you to go to the nearest town and get
your flat fixed rather than driving with the donut. They also say to limit
your speed to 50 mph or less.
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