I think I figured out why 185x70r14 tires started rubbing when I
switched from 60 spoke wires to alloy knockoffs.
The 60 spoke wires are 4.5" rims. (ruffly measured and it is what moss
sells.)
The alloy knockoffs are 5.5" rims. (From the moss catalog.)
According to tirerack's site
<http://www.tirerack.com/tires/tiretech/tirespecskey.html#measrimwidth>
The sectional width of the tire increases by about .2" per .5" increase
in wheel width.
So my tires went from 7.2" to 7.6" by the increase in rim size.
The tires on the alloys also seem to be a bit bigger otherwise as well.
I still have the same tires mounted on the worn out wires.
The old ones measure at 7.2" (I put the tire on it's side and set a
board across the tire and measured the height of the board from the
ground at 7.18"
The other tires, on the alloys measure at 7.68" using the same method.
So, on my car, 7.2" sectional width 185x70r14s don't rub. 7.7"
sectional width 185x70r14s rub the outer fender on dips/bumps so bad
they ruin the tire.
On a side note, I also found a miata site on tire size calculation that
allows you to put in numbers and see the calculated tire sizes. Works
for all tire sizes, no "miata related features".
<http://www.miata.net/garage/tirecalc.html>
I would like to try some 195x60r14's but am afraid they would have the
same rubbing problem even though they are shorter.
--
Andrew Lundgren
lundgren@byu.net
http://www.Lundgren.us
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