Thor Forums

[kmhappel]

How great to have the opportunity to look at so many views from the members here and extra thanks to gmtech for hanging it all out with me...

The GCWR is 22,500lbs. 8,000lbs is the tow weight. The chassis GVWR is 14,500 lbs. The Ford specification is a front axle load of 4,900lbs. and a rear axle load of 9,600lbs. A standard 225/75R16 tire with 10 ply E load range construction is rated at 2,469lbs. at 80 psi. That means the front tires provide 4,938lbs of load capability. The rear axle tires provide 9,876lbs. Probably just fine if you don’t max out he load.

Upgrading to a larger tire like a 17.5 inch diameter wheel with a 14 ply G load rating brings the problem of tire price and finding replacement tires. That’s why Rickson is a thousand dollars more expensive than a 235/85R16 tires with Alcoa wheels.

The next issue is the front wheel for a 235/85R16. The use of a SRW wheel places the tire outwards from the standard placement by 4.5 inches and the increase in the wheelbase is probably useful. But if it requires changing the exterior, Thor may find that a warrantee ending action. Don’t have an insurance opinion yet either. However, using the Alcoa rims for the rear and the matching front rim that also centers the tire over the bearing (providing a 4.5 inch offset like the delivered wheel eliminating the wider wheelbase but also eliminating (as gmtech mentioned) the bearing leverage and the need to trim the wheel well.

These Michelin 235/85R16 are also E load level tires and will provide 3096lbs. each at 80 lbs. The matching Alcoa front and rear wheels or hubs will deliver 2780lbs. at 95psi. This yields 5,560lbs front and 11,120lbs rear. What is also clear is that the larger tires will also fit on the Thor supplied wheels/hubs. What is also clear is that the tire ratings are 6,192 front and 12,384lbs. rear. The tires are going to work much less hard at full load.

I think the larger tires are important for the clearance they provide. As the Thor Vegas 24.1 Manual relates, the replacement of the rear struts with wheels is advised to stop them digging in when the tail end hits a rapid change in rise. I happen to live in an area where I will have to navigate a number of hills with sharp changes in rise.

The Alcoa SRW wheel looks great and wheelbase is also a huge plus but requires more thought for me. I am going to see what the load rating of the standard Thor wheels/hubs are. The larger tires may fit them just fine.

If tuning means 5-star tuning and the like, I think it is the single best thing that can be done for performance but it is illegal in CA (The Ford engine is detuned for emissions control reasons).