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[quote=Charles Lasitter;9034]Tires have specs for section width, rim width, and rim width range.
(Plus lots of other stuff).
Looking at a Pirelli PZero Nero 225/45-WR17, it lists a rim width of
7.5" and a rim width range of 7-9".
If this wide tire were mounted on a 17x7" wheel, it would seem that
the sidewalls would protrude a bit on either side, offering the rim
some small level of protection against curb scrubbing.
That would seem to be a good thing, but what I need to figure out is
if there are any handling / ride considerations for using a 7" rim
versus a 9" rim.
Any implications for sidewall flexing / rolling resistance / contact
patch / "spring" effect on a tire as a car enters a corner?
Tire designers generally expect maximum performance when the tread width (not section width) is equal to or slightly more (say 1/4 to 1/2") than the rim width. Thats why they say the recommended width is 7.5" as the tread width is likely about 7.75 to 8".
Only if you use a 8.5 or 9" rim width will the rim be unprotected as those Pirellis are molded with scuff protecton. But when the rim is much wider than the sidewall buckling takes place in hard sideloads so the rimlimit is 9". Even then I suspect there is enough buckling to reduce performance except at very high pressures. Which you will need to 'flatten' out the tread. As the beads are widened the tread tends to bow up in the middle so additiobnal tire pressure is needed to flatten it out for good road surface contact.
In short, stick with 7.5 +/- 0.5" rim width.
good luck.
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