wheel size

It's not the 60 series by itself that's the problem.

The "series" is the sidewall height, but it's listed as the percentage of the width of the tire.

For example, a 245/60/15 means that the tire is 245mm wide, and the sidewall height is 245 x .60 = 147mm. If you want the height, you double the sidewall height, convert to inches, and add the rim diameter.

147x2= 294mm =11.57"

So the tire height is 11.57+15= 26.57"

The width of the tire has just as much of an effect on what will fit as the series does.

On a 5.5" rim you can go as wide as a 215, but it has to be a 70 series. If you're running 14's that's fine, if you have 15" rims then that tire will work on the rear, but not on the front (it's 26.9" tall).

As far as 245/60's on a 5.5" wide wheel, yes, that would be totally wrong, and potentially dangerous. You can usually get by if you're within a 1/2" of the recommended range, but more than that can cause abnormal wear and handling.