Heavy truck tyres

Any place to get heavy truck tires? Looking at getting an RV which uses the smaller tires (19.5" rims instead of 22.5"). Currently has 225/70 (or 75) when it originally came with 245s.

Managed to get a read on manufacture date on one of them (Continental HSR) and they're 2010 vintage so probably time to change, given truck tires are inflated to 95 PSI.

U.S. price is USD$345 and I'll need 6.