Most of the tire companies provide a spec chart for a given model of
tire. Among the other data provided is a range of allowable rim widths
for each size of tire in that model.

7" is nearer the upper end of width for a 205, 6" is the measuring width
they use for the spec table for your Nokians. Allowable range is
5.5-7.5.

6.5" is right on for a 215 in many tables, just look up a given tire to
check.

Mark

Gary Stearns wrote:
>
> I'm running 205/65-15 on 15 x 7 wheels now.  This is the closest in diameter
> to the original (on mine) 205/70-14.
>
> Your idea of 215's on 15 x 6.5 strikes me as too wide a tire on too narrow a
> wheel.  The weight of the Westy will cause the tire to "roll under" in
> corners.  Don't use anything but light truck or reinforced tires.  I've used
> passenger car and reinforced tires.  The difference in stability is amazing.
> I'm running Nokian NRH2 tires now.  I'm very satisfied. Go to
> http://www.nokiantires.com/indexen.html
>
> Gary
>