The HC's with their 6K axles and 6 lug wheels represent the dilemma members faced back when the biggest Montana came with 6K axles. The ST's would blow and there were many, many questions about what to replace them with.
There is a MOC member Lonnieb who is a tire dealer and a great guy. A number of MOCers traveled to his shop in Texico, New Mexico to buy tires due to his participation and advice here. While he hasn't been active on the forum recently, he was a real tire guru who always tried to help members with their tire questions. He made what I consider the definitive post on LT v. St tires back in March 2013. He re-iterated the advice numerous times here in different postings. Here is the pertinent posting:
Quote:
quote::By Biggjb
Lonnie, I have a 2009 2980RL and currently have GY Marathons ST235 80R16 E rated. Fully loaded it is 14400 lbs. I always ensure the tires are 80 psi and check that every morning while on the road. I had one blow-out last year on a very short haul, and I have just went over 1200 miles with no mishap. But the concern of a blow-out on the I-95 was constantly in the back of my mind. I have heard LTs would work better.
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The specs I came up with for your trailer are as follows;
Dry shipping weight - 10,415 lbs.
Cargo carrying capacity - 3,940 lbs.
Pin weight - 2,275 lbs.
Adding the dry shipping weight and the cargo carrying capacity together I get 14,355 lbs., which is pretty close to what you listed. Subtracting the pin weight from 14,400 I come up with 12,125 which calculates out to 3,031 pounds per tire.
The most common LT size to replace the ST, is LT235/85R16. This size is approximately one inch larger in diameter and the same width as the ST235/80R16 you are currently running. Another size would be LT245/75R16 which is three tenths inch shorter and four tenths inch wider than what you currently have. Both of these sizes, in the E load range, have a maximum load rating of 3042 pounds at 80 psi. I know this looks like you would be pushing the limits, but that isn't the case. Unlike the ST rated tires, the LT has a large reserve capacity built in, meaning the maximum load rating on the tire is significantly less than the tires actual capacity. This is done due to Federal regulations because these tires must safely carry human passengers at speeds up to 112 mph. ST rated tires are not held to the same safety standards for several reasons, they are NOT legal on motorized vehicles, they are NOT legal at speeds above 65 mph, and most importantly, they are NOT legal to carry human passengers at ANY speed.
A good quality, name brand LT tire, in the E load range will serve you well. Below is an updated list of my personal preferences, along with a "ballpark" price, not including installation. Prices vary across the country, and even from dealer to dealer, so shopping around a little would be a good idea. I recommend going to a REPUTABLE dealer, one that sells a lot of tires, one whose main business is tires.
LT235/85R16E
1. Michelin XPS Rib - $314.00 each.
2. Bridgestone Duravis R250 - $250.00 each.
3. Bridgestone Duravis R500 - $206.00 each.
4. Firestone Transforce H/T - $162.00 each.
5. BF Goodrich Commercial T/A - $188.00 each.
Lonnie's Post is on Page 2 of this link
I am sure the prices are not current, but the recommended tires are.