Help me understand weights and tire rating.

enblethen wrote:
10400 deducting 1125 pounds of tongue weight leaves 9275 on the trailer axles, divided by 4 equals about 2318 pounds per tire (205/75-15 are good for only 2150 per tire. 225/75-15 are good for 2540 per tire.
It is real close with the 225 tires. Not sure what kind of clearance is on the rig to go larger tires.
Not sure what axles are on the trailer even if the tires were good.

Guess I missed something. I thought the OP said he had the Load range D 2540 rated tires. That being the case the factory did not sell him a TT with under rated tires. I thought he was asking about that.

There is little doubt the TT designers use the least expensive materials that will do the job.

That is why you need to be diligent with repairs and maintenance.

Given the growth in the industry, this year expected to exceed 350,000 TT and 5vers, there is little incentive to change things.

Only in the RV world is the tongue load considered part of the load capacity rather than a factor of it. On all other trailers a 10000# suspension equates to a 10000# GVW not 11200#. This is one reason TTs have suspension and tire problems. Many are overloaded from day one.

To add to my thinking, the trailer tires must have equal load. If trailer is high in the front it will add weight to the rear tires of the trailer. If it is down in front it will add weight to the tongue and the front tires on trailer.
You might think about using LT tires.

Thank you for the quick replies. I was going to purchase new Maxxis 10ply tires next spring I just wanted to understand where all the numbers were coming from. Thanks again

10400 deducting 1125 pounds of tongue weight leaves 9275 on the trailer axles, divided by 4 equals about 2318 pounds per tire (205/75-15 are good for only 2150 per tire. 225/75-15 are good for 2540 per tire.
It is real close with the 225 tires. Not sure what kind of clearance is on the rig to go larger tires.
Not sure what axles are on the trailer even if the tires were good.

enblethen wrote:
Gross weight is 10400, dry weight is your 8945
1125 gross tongue weight.

This is from a website for your rig

Dry Weight (lbs/kg) 8945 / 4057.5
Payload Capacity (lbs/kgs) 2080 / 943.5
GVWR (lbs/kgs) 10400 / 4717.4
Hitch Weight (lbs/kgs) 1125 / 510.3
Looks to me like you will have issues. You would need to go up to 225/75R15s
Maxxi Tire chart:
TL15713000 225/75R15 10 BSW 28.3 8.9 80 2830 6.0-[6.0]-7.0 9/32
TL15710000 225/75R15 8 BSW 28.3 8.9 65 2540 6.0-[6.0]-7.0 9/32
TL15703000 205/75R15 8 BSW 27.1 8.1 65 2150 5.0-[5.5]-6.5 9/32
TL15700000 205/75R15 6 BSW 27.1 8.1 50 1820 5.0-[5.5]-6.5 9/32

Are you taking into consideration that 1,000 pounds of his trailer weight is supported by the tongue and not by the tires when you say the OP will have issues? Looks to me like when the trailer is at max weight the tires will only be carrying about 9,000 pounds on tires rated in excess of 10,000 pounds. Am I missing something?

Here are the numbers for my rig.

My 25 ft Dutchmen has a max weight of 7700 lbs (GVWR),that is the heaviest load it is designed to carry. The dry weight is 5000 lbs.

The tires are rated 1850 lbs each, so the four tires have a carrying capacity of 7400 lbs. So the manufacturer anticipates at least 300 lbs to be taken up by tongue weight (4%).

The real world numbers, when I am heavily loaded for an extended trip and drive over the CAT scales are; my TT weighs 6520 lbs. my combined axel weight is 5680 lbs and my tongue weight is 840 lbs (13%). Therefore each tire is seeing 1420 lbs. a 430 lb buffer (23%) of its load capacity. I suspect this is the norm for most TTs on the road.

So the question for you is what makes you feel safe 25%, 50% 200% over the design limits. There is nothing mystical in the numbers.

I found I can get the same size tire in the next higher load range for just a few bucks more. Since my current tires are 6 years old and I have put 15,000 mile on them plus whatever the previous owner added, I will probably opt for them. They run 65 psi but if that is too rough a ride on the TT, I can reduce them to 50 psi and maintain the current load rating.

None of this means anything of I run over a road hazard, which is how all of my flats have occurs in the last 30 years of driving, including the ones on my TT and PUP.

Gross weight is 10400, dry weight is your 8945
1125 gross tongue weight.

This is from a website for your rig

Dry Weight (lbs/kg) 8945 / 4057.5
Payload Capacity (lbs/kgs) 2080 / 943.5
GVWR (lbs/kgs) 10400 / 4717.4
Hitch Weight (lbs/kgs) 1125 / 510.3
Looks to me like you will have issues. You would need to go up to 225/75R15s
Maxxi Tire chart:
TL15713000 225/75R15 10 BSW 28.3 8.9 80 2830 6.0-[6.0]-7.0 9/32
TL15710000 225/75R15 8 BSW 28.3 8.9 65 2540 6.0-[6.0]-7.0 9/32
TL15703000 205/75R15 8 BSW 27.1 8.1 65 2150 5.0-[5.5]-6.5 9/32
TL15700000 205/75R15 6 BSW 27.1 8.1 50 1820 5.0-[5.5]-6.5 9/32

This trailer sounds like a good candidate for 16" LT tires.