Speed, all the major tire mfr are pretty reliable as far as quality goes. I use Michelin with never any problems and less $ than the G670?s. Different mfr brands will ride and handle a bit differently based on durometer and tread pattern but I still feel this is a minor difference, not a $100/tire consideration as some mfr would have you believe. Again, JMO.
Everyone has an opinion on mfr based on their own history all though personally I think there are only 3 things that matter. 1) Are they the correct load rating for the actual load of my vehicle. 2) Can I get a replacement on the road, if needed (this eliminates a lot of small mfrs) so I don?t have to mix brands. 3) Are they price competitive incl FET, mount, balance, etc.
When you purchase these tires first thing you have to require is that the date codes are not over 3 months old because our age out, not wear out. This is requirement for MH owners and you will not be the first to request this. If they can?t comply go elsewhere.
Where you purchase the tires does not need to be where they are installed. Many local dealers are happy to get the labor to install even if they do not sell or can?t be competitive on the price of the tire.
You can purchase the tires even at a shop that cannot install them because of their size, such as Costco, Firestone or Discount Tire, who do not install over 19? if I recall. They can order what ever size you need so base it on price delivered. If you are a member of FICM they have a factory discount on Michelin?s also. I?ll look up the info if someone doesn?t chime in here with it.
Michelins say they are good for 10 yrs. I do mine at 8 and everyone has an opinion on this also. Weight your coach, incl the toad if you have one and consider the damage if you have a blowout. You have to find your own sweet spot based on loads and inspections. A MH is not the same as an OTR vehicle that normally runs until failure. When you remove your old tires ask the dealer if he will purchase them as used OTR trlr tires.
Consider whether you wish to do balancing and what type. Most on this size use the beads and of course incl the filtered steel valve stems in the overall purchase. These items can add $25+ to each tire cost.
I would also consider a TPMS system down the road but that?s another subject. This should give you enough info to get started! Welcome to the forum also.