There is a local guy selling 15x7 Rallye wheels. My question is just this. Can you put a tape measure on the wheel across the front and measure 15" and then across the beads and expect to see 7"?

edit. Also how would you measure the backspace. From the back of the rim into the back of the center section?

Thanks

Across the front of the wheel the measurement will excede 15" (the base of the beads is 15")

The 7" dimension is inside-to-inside of the beads.

width is between the beads at the base of the beads. For backspaceing put a straight piece across the back & measure down to the wheel flats next to the bolt holes where it touches the axle flange. As said "offset' is a different dimention & related to absolute center & used far less frequently than "backspace"

In many cases, when measuring diameter, the number that you get will often be 1 1/4" larger. A 15" wheel will be about 16 1/4". When measuring width on steel wheels, the outside to outside number will often be 3/4" to 1" wider than at the bead.
On ALUMINUM wheels, measuring width from the outside results in a measurement about 1" to 1 1/8" larger than the measurement at the bead. This is because the aluminum has to be thicker to equal the strength of the steel wheel.

Thanks for the info.

often on steel wheels the size 15 x7 or whatever it is will be stamped on the inside of the rim also.