New member(class C) + question about tire change

I have yet to buy new tires for our 8 year old rig. My plan is to buy fronts first as we practiced with our first motor home. So far we have no cracking or other degradation. The rig is stored indoors, concrete floor, dark, cool in summer, warm in winter. The RV is lighter as well, so the psi is never more than 70 on any tires. As long as there is good thread and sidewalls, I'll keep using them.

I feel that lack of outdoor exposure helps immensely.