Tire questions, whats your opinions?

[Goneracin]

So we are getting ready to head out tonight for our first trip with the new TT. I have been doing a lot of preparations and am very confident in my setup. The original tires are load range C ST tires. To the best of my knowledge these have a max speed rating of 65 mph. The trailer is as listed in my signature, and I would say it is loaded to its GVWR, so around 6000lbs. I dont like to tow at or close to the limits of my truck or weight ratings, and the load range C tires are fine for the load, (1700 each total 6800) but the speed concerns me. My truck is not happy towing at 60 mph, too low of a gear due to the lift.

So the question is, how sensitive is that 65mph rating? I cant find a rating on the tire, just general info online that says all ST tires are rated at 65. Do they make them in a higher rating? Should I just switch to a load range D? If so whats the speed rating on those tires?

I know you shouldn't exceed the 65 mph speed, and I will stay as close to it as possible, last thing I need is a blowout. What should I do for trips later on so I can tow at a more comfortable speed?

[Franka548]

Goneracin,
The 65mph is the correct speed rating of the ST tires. That doesn't man that at 66mph that they will disintegrate. If your truck likes to run in the 64 to 66 mph range, then go for it. Myself, I wouldn't run much over 66 mph anyways pulling a trailer.
As far as upgrading your tires, the speed rating doesn't matter what load range, most if not all ST tires are speed rated at 65 mph. Make sure your air pressure in the tires is right and check the heat after you run awhile. The tires will be warm, but shouldn't be hot to the touch on the sidewalls. Mine run 130 to 145*, they are load range H. if you have an Infrared gun, yours should run below 140* to be safe. Also, if you are that close to your GVWR, I would suggest that you make a trip to your local truck scales to find out exactly what you weigh.
Frank

[nomad297]

Originally Posted by Franka548

Goneracin,
The 65mph is the correct speed rating of the ST tires. That doesn't man that at 66mph that they will disintegrate. If your truck likes to run in the 64 to 66 mph range, then go for it. Myself, I wouldn't run much over 66 mph anyways pulling a trailer.
As far as upgrading your tires, the speed rating doesn't matter what load range, most if not all ST tires are speed rated at 65 mph. Make sure your air pressure in the tires is right and check the heat after you run awhile. The tires will be warm, but shouldn't be hot to the touch on the sidewalls. Mine run 130 to 145*, they are load range H. if you have an Infrared gun, yours should run below 140* to be safe. Also, if you are that close to your GVWR, I would suggest that you make a trip to your local truck scales to find out exactly what you weigh.
Frank

I couldn't have said it better, myself.

Bruce

[Goneracin]

That all sounds like I figured. I did check the tires last night, they are all at the max 50 psi. I was thinking of upgrading the load rating of the tires because I like to have a margin of error. I understand that 66 doesn't mean they will blow, but the more over 65 I go, and the longer I stay there, obviously the chances increase.

I agree about the scales, I've been meaning to get to one just for my own knowledge. However, I might have worded it wrong, I know I am no where near over the limit of my tow vehicle CGVWR, I'm just guessing we are getting close to the max of the TT. I'm only guessing so because I know we filled the water tank, fridge, storage compartments....etc.

I will do as you said and stop after about 10 to 15 miles at highway speeds and see what the tires feel like.

Thanks for the input, makes me feel more comfortable that my thoughts are pretty much correct.

[nomad297]

Another thing to consider is the ambient temperature and asphalt temperature. On a hot and sunny day the road surface temperature can get much hotter than the ambient temperature and your tires feel the heat. These were the conditions on the day I had three separate blowouts driving 65 to 70 mph. This was before I knew that ST tires are all rated for 65 mph.

Bruce

[Goneracin]

Originally Posted by nomad297

Another thing to consider is the ambient temperature and asphalt temperature. On a hot and sunny day the road surface temperature can get much hotter than the ambient temperature and your tires feel the heat. These were the conditions on the day I had three separate blowouts driving 65 to 70 mph. This was before I knew that ST tires are all rated for 65 mph.

Bruce

Good to know, that slipped my mind. Good thing it will be cooler this afternoon.

[chaps2018]

Higher load range will give you more margin period.

1)They will have better thermal performance
2) more robustness to air pressure differences (ie, my load range D were 65psi max, my load range E are 85psi max
3)better long range wear and tear if you do lots of low speed turning such as backing in the driveway, storage, etc (due to thicker sidewalls).

That said, higher load range doesn't give you a license to exceed the 65mph rating, just more risk mgmt options.

[Goneracin]

Originally Posted by bjlakatos

Higher load range will give you more margin period.

1)They will have better thermal performance
2) more robustness to air pressure differences (ie, my load range D were 65psi max, my load range E are 85psi max
3)better long range wear and tear if you do lots of low speed turning such as backing in the driveway, storage, etc (due to thicker sidewalls).

That said, higher load range doesn't give you a license to exceed the 65mph rating, just more risk mgmt options.

Yep, thats pretty much why I think I will upgrade to load D. Does anyone know of a load D tire that has a higher speed rating? There must be some out there that are rated for 70 mph, or maybe even 75, (not that I plan to go that fast, I just like to have more of a margin as stated above)

[Texastbird]

Racer, if you go to a higher load range, then you will have to check your wheels to see what they are rated for. I just went through this scenario and decided that since I wasn't ready to replace my pricey aluminum rims, I just went with the same load range. (My original tires were just about worn out) I think a margin of speed is built into the 65mph rating. I've been passed by trailers and 5th wheels when I was running my usual 62-63 mph, like I was sitting still. Obviously they are getting away with traveling faster than the 65mph of the ST tires. But I can guarantee their fuel mileage sucks big time going that fast. Also I don't fill my water tank full before a trip, just enough for what we might use along the way. This will save more weight than you think.

[Goneracin]

Good point texastbird, I forgot to mention that part. The wheels now are steel wheels, so I would be upgrading to an aluminum wheel as well if money provides.

Yeah, Ive seen plenty of people going well over that speed, and Im sure there is a margin of safety, I just figure why not get one thats rated higher if its available.

As for fuel mileage, my tow vehicle starts out at a major disadvantage there. I have an 8 inch lift and 37 inch tires. Combine that with the stock 3.73 gears, and that seriously hurts the towing capability of the truck. Some day I will regear, but as always its $$$. Anyway, at 55 my engine RPM is too low when I hit a hill and I cant get much boost out of the turbo, at 70 its a different story, lean into the throttle, turbo spools up, and continue the climb. faster speeds would help the turbo issue more, but then safety becomes way too much of a risk as we all know.

Last year we traveled from CT to Pocono PA with a rental trailer, almost the same trailer, and we averaged 10 to 11 mpg even with all the hills. Not the best, but due to the lift and tires ill take it.

Thanks for the help

[FastEagle]

Originally Posted by Goneracin

So we are getting ready to head out tonight for our first trip with the new TT. I have been doing a lot of preparations and am very confident in my setup. The original tires are load range C ST tires. To the best of my knowledge these have a max speed rating of 65 mph. The trailer is as listed in my signature, and I would say it is loaded to its GVWR, so around 6000lbs. I dont like to tow at or close to the limits of my truck or weight ratings, and the load range C tires are fine for the load, (1700 each total 6800) but the speed concerns me. My truck is not happy towing at 60 mph, too low of a gear due to the lift.

So the question is, how sensitive is that 65mph rating? I cant find a rating on the tire, just general info online that says all ST tires are rated at 65. Do they make them in a higher rating? Should I just switch to a load range D? If so whats the speed rating on those tires?

I know you shouldn't exceed the 65 mph speed, and I will stay as close to it as possible, last thing I need is a blowout. What should I do for trips later on so I can tow at a more comfortable speed?

There is a much more robust trailer tire that is only manufactured in three 14” diameter sizes, all LRD. It’s a commercial European designed truck tire especially designed for trailers and has a 99 MPH speed rating. See the reference below. Note; the C after the size description means it’s a commercial design. The load range is described elsewhere.

That tire’s load capacity and air pressure rating may require upgraded rims.

http://www.tirerack.com/tires/tires.jsp?tireMake=Kumho&tireModel=Radial+857&side wall=Blackwall&partnum=0R4857&tab=Sizes

RADIAL 857 - Kumho Tire USA, Inc.

FastEagle

[Goneracin]

Thats worth looking into, plenty of margin for safety. Thanks

[Cypressloser]

Please keep in mind that a tire upgrade does nothing to absorb the additional stress caused by tire bounce and rough roads on the trailer axles and spindles, suspension, leaf springs, trailer frame etc. that occurs at higher speeds.

[Goneracin]

True Cypressloser, Im not looking to be able to go 99 MPH though, just want a little more comfort zone if I push it to 70 before hitting a big hill.


My camper list tire sizes as 205/75R14C, but those tires are only listed as 205R14C. How do I know if the sidewall height is correct? Maybe Im missing something here