I have been using Discount Tire in the Denver area for some 20 + years now ... they were the first ones I could find who used a torque wrench on the lugs ... was getting tired of needing new lugs back then. ;D
I have been very happy with their service over the years, in fact tires are probably about the only thing I don't shop or over shop for. Having said that when I needed to replace the tires on our used mh I did shop around for Goodyears ... Wingfoot, Farm co-op and Discount. Got the G-670's from them and price was competitive (and they said they would match). We have the 225/70R/19.5's and they have been just fine so far, due for a rotation which will be no charge.
So I would recommend Discount ... there may be stores that aren't equipped to handle the motor homes but mine seemed to have no problem.