[PHudson]

Yes, I know this has been discussed many times before but after re-reading I'm still confused.

Standard 15" are 6 inches wide, 4x108, offset 30, central bore 65, I think.

The 4x108 and the central bore stay the same, presumably.

How does the offset vary? With changes in width only, or also in size? What combinations of size/width/offset are known to fit without rubbing?

From the various options, what width/offset would people recommend for 16" or 17" wheels?

 

[sgould]

If you want to keep the centre of the tyre in the same place, use the same offset. But, this will sometimes move the outside edge of the tyre into conflict with the wing.

So, it's more usual to change the offset by half the increase in wheel width so that all the extra width is on the inside. A one size increase in width is usually OK since the original tyre often left room for fitting chains.

 

[PHudson]

Originally posted by sgould:
[qb]So, it's more usual to change the offset by half the increase in wheel width so that all the extra width is on the inside.  [/qb][/b]

OK. So now I have a units problem. The width is in inches. Is the offset in mm? And if the width goes up, does the offset go up or down?

 

[mark e]

If the width increases by 1", reduce offset by 12mm... etc.