That's tire width, not wheel width.

Passenger and LT tires are mm / % - in
205/50-15 is 205mm wide, sidewall height is 50% of width, and it fits a
15" rim.

Larger truck tires are specified in diameter x width (in inches) - rim
diameter. i.e. 31x10.5-16

Wheels are in x in
Offset is -mm
(ET30 is a -30mm offset by most descriptions)

Backspacing is in inches.

Offset and backspacing are used for different things. You pay attention
to offset for wheel bearing load, and backspacing for clearance. (though
they are obviously linked)

Actually, wheel diameter is in whatever's appropriate, but the only
metric wheel diameters I know about were the TRX rims of the late 70's
and early 80's.

Kim Brennan wrote:
> 205 is inches? Bloody wide tire.....
>
>
> On Mar 14, 2005, at 1:38 PM, JordanVw@AOL.COM wrote:
>
>> here is stupid question i always wondered about..   why is wheel
>> diameter and
>> width always in inches, but the offset is in Millimeters?       just
>> always
>> wondered why.
>
>