G60-15 replacement question

There are a couple of ways of looking at the situation of replacing the G60 tires.

1. Since tread width varies from manufacturer, look at the cross-section width. This typically is the widest part of the tire. It is also the part of the tire used to calculate side wall height appropriate to the aspect ratio. A "60" series sidewall is 60% of the height of the cross-section width.
2. Stay with the same aspect ratio and go for the same load bearing limits. Typically, bias ply tires have higher load limits than radial ply tires at the same number of plys, materials, and cross-section. To re-capture lost load limits, it is normally necessary to go up two sizes on the radial tires.