I had the 235/80r22.5 xrv Michelin's on my 05 when I purchased it, changed them with Toyo M154 245/75 22.5 last year, balanced all 6 with Dyna Beads and had the front end alignment last year, so far I'm happy with my purchase. Do a search on the WorkHorse Chassis Form for more info. I think they recommend increasing the caster to make it track better, you can call Brazel's and they will enlighten you.
Mike, Lora and Bebe
05 Safari Simba 37 PCT, WorkHorse W22, Koni FSD, CrossFire, Rear Trak-Bar, SG2
Ready Brute w/ Ready Brake, Safe-T-Plus, 05 GMC Envoy