tire max load question

[jgroff]

here it is.

the tires on my trailer are 205/75/14 load c (1740 lbs max at 50 psi)

so total carrying capacity of - 6960 lbs.

my trailers gvw - 7725 lbs.

I pointed this differecne out to the dealer. they think it is fine because the tongue weight will come off the gvw of the trailer. does this make sense?

I would think and by all that I have read, you want a tire that exceeds your gvw.

thanks for any info

[dcheatwood]

Yes. Makes sense, but I thought LR C tires maxed out at 44psi.

[BarryD0706]

It is correct to subtract the tongue/pin weight. They didn't leave you much margin though. I think I would upgrade if practical.

[Dave_Monica]

The manufacturer usually (not always) sets the camper's GVWR by adding the dry tongue weight, or pin weight in the case of 5vers, to the axle(s) load rating.

When determining which load rated tires are required, you would want tires that would exceed the camper's axle rating...your choice how much safety factor you want.

For clarification, load range C tires have a maximum inflation pressure of 50 psi...load range D - 65 psi, load range E - 80 psi. Passenger tires have maximum inflation pressure of 44 psi.

Dave

[dannyabear]

Mine is the same, weighed it and has 6613 on the tires; Fixin to order a set of Kumhos 857 before I have trouble..

[dcheatwood]

Originally Posted by Dave_Monica

The manufacturer usually (not always) sets the camper's GVWR by adding the dry tongue weight, or pin weight in the case of 5vers, to the axle(s) load rating.

When determining which load rated tires are required, you would want tires that would exceed the camper's axle rating...your choice how much safety factor you want.

For clarification, load range C tires have a maximum inflation pressure of 50 psi...load range D - 65 psi, load range E - 80 psi. Passenger tires have maximum inflation pressure of 44 psi.

Dave

Duh! Thanks Dave. I confused my truck "p" tires with RVs "C" tires.

[jgroff]

Originally Posted by dannyabear

Mine is the same, weighed it and has 6613 on the tires; Fixin to order a set of Kumhos 857 before I have trouble..

I am thinking the same thing. I haven't signed the papers for the trailer so I am pushing for them to have the tires changed to d load rated. We will see. If it does t happen I will change them myself

[OldCoot]

Originally Posted by jgroff

I am thinking the same thing. I haven't signed the papers for the trailer so I am pushing for them to have the tires changed to d load rated. We will see. If it does t happen I will change them myself

Don't back down, that's about $500-$600 out of your pocket. Make them balance them also.

[ependydad]

Originally Posted by jgroff

I am thinking the same thing. I haven't signed the papers for the trailer so I am pushing for them to have the tires changed to d load rated. We will see. If it does t happen I will change them myself

It looks like by design on the Grey Wolf 26DBH, there is 13% hitch weight (740 / 5750). That means, at GVWR you have 996 pounds of hitch weight, leaving the tires carrying 6,744 pounds which, while close, is below 6960 (4 tires, aired to max).

Keep in mind, you likely won't be running at GVWR (shocking for me to say- I know!). Figuring on a camper weight of 1,000 pounds over dry - you're at 5,872 pounds of tire weight. If you go with 1,500 pounds over dry - you're at 6,017 pounds of tire weight.

Just some things to think about before running out and swapping tires immediately.

[Tireman9]

Originally Posted by jgroff

here it is.

the tires on my trailer are 205/75/14 load c (1740 lbs max at 50 psi)

so total carrying capacity of - 6960 lbs.

my trailers gvw - 7725 lbs.

I pointed this differecne out to the dealer. they think it is fine because the tongue weight will come off the gvw of the trailer. does this make sense?

I would think and by all that I have read, you want a tire that exceeds your gvw.

thanks for any info

You mean your tires are ST205/75R14 LR-C. With 14" tires there is not a lot of choice. You can go to ST205/75R14 LR-D and have extra tire capacity which means that when you run the tires at 65 they will be underloaded and with that safety margin you might get more than a couple years life.
Remember ST type tires are rated for 65 mph max. That is like an engine Redline on a tach. It's possible to exceed the max speed but you will be doing damage.
You might want to confirm the max load and max inflation limit on the wheels. Get something in writing on these limits.

[Dave_Monica]

I'd wonder what the manufacturer has put on the weight label on the camper per axle...axle weight rating (I'm assuming 3500# axles) or max of 3480# (max tire load x 2). What does the sticker say?

Dave

[Dave_Monica]

I quess I can answer my own question. The max load rating for 205/75/14 C is 1760 lbs, not 1740 lb. I didn't think any manufacturer would put OEM tires on that didn't exceed the camper's axle rating, though just barely.

Dave

[jgroff]

Originally Posted by Dave_Monica

I'd wonder what the manufacturer has put on the weight label on the camper per axle...axle weight rating (I'm assuming 3500# axles) or max of 3480# (max tire load x 2). What does the sticker say?

Dave

The sticker says 3500 lbs axles

[jgroff]

I wonder what would be better. Running the tires that are on it, didn't realize the tongue weight came off of the trailer weight. Makes a difference. Or get d load rated and run either 65 psi or figure the pressure I should have in then to carry that weight. I think running the d rated tires at 65 psi would make for a bouncy trailer

[acadianbob]

Originally Posted by dannyabear

Mine is the same, weighed it and has 6613 on the tires; Fixin to order a set of Kumhos 857 before I have trouble..

I have been running this tire for 2 years; they're AWESOME! It's a D rated 14" tire with a 99 mph speed rating. (Yep, look it up.) They run nice and cool.

My trailer came with 205/75/14 C-rated tires. I changed to Kumho 857s in size 195/82/14 D-rated. This size Kumho will give you exactly the same circumference as your original tire and still give you substantially more capacity. On my trailer, circumference/diameter was an issue as my axles are very close together; only 2" between the tires.

[jgroff]

Originally Posted by Tireman9

You mean your tires are ST205/75R14 LR-C. With 14" tires there is not a lot of choice. You can go to ST205/75R14 LR-D and have extra tire capacity which means that when you run the tires at 65 they will be underloaded and with that safety margin you might get more than a couple years life.
Remember ST type tires are rated for 65 mph max. That is like an engine Redline on a tach. It's possible to exceed the max speed but you will be doing damage.
You might want to confirm the max load and max inflation limit on the wheels. Get something in writing on these limits.

thanks for the info tireman. what would you recommend in this situation. run whats on there? or upgrade to the d rated? would you run the d rated at max pressure?

[Tireman9]

With multi axle trailer I would run the inflation molded on the tire. This will lower the internal shear forces that are trying to tear the belts off the carcass.
There are engineering design computer programs available today that were never dreamed of when the design standards for ST type tires were originally developed decades ago. I have never heard of any RV "assembler" having an engineering design department or staff charged with the goal of designing long term durability into the units they build, so they would not know of these tools.
I asked one of the advance design engineers at a major tire company to run a computer simulation of multi axle trailers and he confirmed that the major forces we see that "bend" tires and axles when you are turning tight radius turns in multi axle trailers are doing hidden internal damage to any tire in multi axle application.
The only way to lower these forces are to significantly lower the tire loading (by 20 to 30%). Since we can't do that then the only thing owners can do is to increase the inflation to the number molded on the tire sidewall.

[OldCoot]

Originally Posted by jgroff

thanks for the info tireman. what would you recommend in this situation. run whats on there? or upgrade to the d rated? would you run the d rated at max pressure?

Upgrade to LR D tires and run max pressure stamped/molded on sidewall. You shouldn't notice much difference in bounce.

[jgroff]

thanks everyone. load range d 205/75/14 aren't a common tire and the dealer said they can't find them so the dealer is going to swap my tires for 215/75/14. which has 1870 lb load capacity. which makes me a lot more comfortable. so I should be good. even at gvw of the trailer the tires have 10% more capacity and realistic weight I will have about 20% more capacity.

[dannyabear]

Originally Posted by jgroff

thanks everyone. load range d 205/75/14 aren't a common tire and the dealer said they can't find them so the dealer is going to swap my tires for 215/75/14. which has 1870 lb load capacity. which makes me a lot more comfortable. so I should be good. even at gvw of the trailer the tires have 10% more capacity and realistic weight I will have about 20% more capacity.

Kumho 875 or Hankook RA08 is only brand I could find that is a 'D' rated tire

Either of them is hard to find in this part of the country, had to order from Tirerack