The 19.5's will cost you more up front, but, probably less in the long run. Depends on whether you think you need 5k per wheel where the 4k may be adequate.
285/75-18 and 295/70-18 are both E129(4080lb) rated but that will be over the rating of your rim which is probably 3600. If you want over 4k 19.5 is your only option.
I had a set of Toyo 285/75 R17 128S with the 3970lb rating. I got 48K miles out of them rotating about every 10K. Toyo doesn't make that specific tire anymore. It is now a 121S with a 3195 rating.
For the size of a 285/75-17 tire, it sure seems that a maximum capacity of 3,970 pounds makes more sense. I'm looking into my first set ever in this size. Though I'd prefer the higher rating, 3,195 is enough for my uses.
If you are looking for a stronger wheel tire combination; I have found one for the 17" wheel and tire.
I am running a set of Mickey Thompson SideBiter II wheels; 17X9, bolt pattern 8X6.5 with back spacing of 5 inches and zero offset rated for 3640 LBS each. I am using a set of Nitto Dura Grappler tires, LT285/70R17 E 126R, with a weight rating of 3750 LBS at 80 PSI. I run the tires at 70 PSI max; which put the tire support load weight under the wheel max weight. The tires at 70 PSI are rated at 3415 each. This is more than adequate for my needs in supporting my trailer when towed.
Jim
I was at Les Schwab today, they are the dealer around here if you want Toyo or Nitto. I asked about getting M608z 19.5 Toyo and depending on size, are rated G (5k lbs) and H (6k lbs) Since the only wheel they can sell me is the Vision heavy hauler super single whatever Chinese made cast aluminum rated at 4500 lbs, he said they can;t match those tires to that wheel since the load rating of the wheel is not up to the tire specs. I am using the Toyo MT's now in a 35"/18 rated 3650 (IIRC). to haul my camper, and tow a flatbed with my jeep on it. I am pretty close to pushing the limits of these tires before I hook up my trailer, with just the camper, me and my dog and full tank of fuel (56 gallon Transfer flow). I am nervous about this set up when towing. I wonder if the Nitto 4k lb rated in a 18" or 20" would be the way to go, since the 19.5 is really tough to justify without spending huge $$ on custom forged American Force or equivalent wheel. Any advice from you regular hauler types thanks in advance.
The LT tires are warranted for 50K. The P's carry a 65K warranty.I had a set of Toyo 285/75 R17 128S with the 3970lb rating. I got 48K miles out of them rotating about every 10K. Toyo doesn't make that specific tire anymore. It is now a 121S with a 3195 rating. I just bought a set of 5(full size spare). They are very quiet until you get to about 80mph. Then the noise is just noticeable. They also changed the tread pattern to be much more aggressive. If it were any more aggressive it would look like a mud tire. New warranty is 65K. Using GPS and construction zone radar to check speed I used Smarty to adjust tire size to 33.8. Just .1 smaller than mathematically running the numbers. Until they do me wrong, I will continue to purchase Toyo tires.
The new Terra Grappler G2's are supposed to wear 40% longer due to a harder rubber material.I run 275/65 20 LRE NItto G2 tires on my 06. Run 80 PSI in f / r for heavy towing. BMF wheels.combo good for 3750 per wheel / tire. I pull G/N trailer with 15 to 16K of hay. Much more stable with 20's than stock 17s. I air down to 60R 70F for normal driving. A bit bumpy on my gravel road, but not bad. Problem with Nitto is wear, had several sets and hard to get to 30K. Going to BFG AT K02 next couple months for winter use.
Good Luck
.Luke