On 4/29/11 we did some tire shopping at our local(San Antonio) Sam's Club & Costco. This time we're purchasing 8 tires for a 2000 Signature. Its heaviest loaded axle is the steer, 13K #s.
I found that both have good prices, but availability is limited. Also, neither mounts, balances, or installs 22.5 tires. Costco sells Michelin, Bridgestone/Firestone. Sam's Club sells Michelin, Goodyear/Dunlop.
Costco: in stock @ warehouse
2 Michelin XZA2 295/80-22.5 H rated = $513ea + local tax.
6 Michelin XZA3 11R-22.5 G rated = $472ea + local tax.
2 Firestone FS507 11R-22.5 H rated = $432ea + local tax.
6 Firestone FS507 11R-22.5 G rated = $410ea + local tax.
Sam's Club: in stock @ warehouse
8 Dunlop SP160 11R-22.5 H rated = $330ea + local tax.
Dunlop SP160 295/75-22.5 G rated = $324ea
Michelin XZE2 11R-22.5 G rated = $476ea
Michelin XZA3 11R-22.5 G rated = $494ea
Michelin XZA2energy 295/80-22.5 H rated = $575ea
Michelin XZA3 275/80-22.5 G rated = $500ea, H rated = $517ea
Michelin XZE2 275/80-22.5 G rated = $472ea, H rated = $503ea
Goodyear G670 295/80-22.5 H rated = $630ea
Goodyear G287 11R-22.5 H rated = $653ea
We ended up buying from Sam's Club 8 Dunlop all position SP160 H rated 11R-22.5s. They both call a warehouse for availability. Sam's Club special orders them after you hand over your $$$.
We hope this helps