Tires: Tires, rim widths, snow tires

Question
Can 235 45r 18 snow tires fit on rims that have 255 55 r 18 radials

Answer
Dear Robert,
Thank you for using AllExperts.
Every tire size has a range of rim widths (minimum and maximum) that it may fit on according to industry standards (regardless of tire brand).  Here are the approved rim widths for the two sizes you mention:
235/45R18:  7.5", 8.0", 8.5", 9.0"
255/55R18:  7.0", 7.5", 8.0", 8.5", 9.0"
All wheels will have the rim width stamped somewhere on the wheel, such as: 18 8.0, or 18X8.0 (18 inch diameter, 8.0" rim width)

As long as the wheels with the 255/55 tires have a rim width as described above, you're OK.

If you have any further questions, or if this is not clear, don't hesitate to contact me again.

DT