Community Forums

mrsportys · 11-25-2017, 09:50 AM

I have the Demco ss tow dolly. I had ( came with) Carlisle radial tires on it before. It stated to load tires to 50 psi I did. The road rating of the dolly only states 55 mph on the road. Rarely happened on the interstate. More like 65-70 mph.
After 11,000 I decided to change to a Goodyear endurance 8 ply radial ( more of a car tire 205/75 r14) tire. “D” rating ( max speed now 75+).
The maximum pressure states 65 psi. It states nowhere what psi to put it at. My load vehicle is a 3500lb Toyota Avalon which we’ll add a few pounds too . Gas tank kept at half or below.
Any thoughts on psi for these new tires. I hate to put at max, drive, overheat them past max psi and they blow. Thoughts?
Thanks!

BFlinn181 · 11-25-2017, 09:58 AM

The tires Max PSI is a cold rating, tire can handle the pressure increase from rolling heat increase. Since only the front axle is on the dolly, gas level and anything in the trunk will reduce front axle loading. I wouldn't think you need maximum inflation, but without weighing the load I wouldn't suggest a PSI.

vettenuts · 11-25-2017, 10:47 AM

Too high a pressure will also bounce the dolly more as well. You really need the loading chart from Goodyear to determine the pressure.

alank · 11-25-2017, 06:54 PM

Logical thinking would be if it's a car tire, why would it need any more air than it would need if it was mounted on the front of your car? You might add a couple of pounds for the added weight of the dolly.

Ray,IN · 11-25-2017, 09:40 PM

Quote:

Originally Posted by alank

Logical thinking would be if it's a car tire, why would it need any more air than it would need if it was mounted on the front of your car? You might add a couple of pounds for the added weight of the dolly.

Aah, now you're confusing things by using logic.

What would the dolly weigh- maybe 350#/weight of two front seat occupants? Man you nailed it!

twinboat · 11-26-2017, 04:34 AM

My thought is that you are not going to overheat a tire if filled to max sidewall pressure, while going down the road.

They list a max pressure so you don't go over it. All of the heat and loading is taken into consideration when they do that. As a matter of fact, an under inflated tire will run hotter.

You stated that the road rating is 55 MPH. Was that on the tires or the dolly ? If it's on the dolly, new tires won't fix that.

If you can't find a tire chart, run them at sidewall pressure.

marjoa · 11-26-2017, 05:53 AM

Quote:

Originally Posted by mrsportys

I have the Demco ss tow dolly. I had ( came with) Carlisle radial tires on it before. It stated to load tires to 50 psi I did. The road rating of the dolly only states 55 mph on the road. Rarely happened on the interstate. More like 65-70 mph.

Well Mr sporty pants....when I started reading your post I immediately started to cringe. I thought, here's a guy that has a 55mph rated dolly and tires and he goes 65 to 70mph on that. Now he's got 75mph rated tires so in his mind he's probably thinking he can safety go 75 or 80. With all the video's, pictures and other posts I've seen of the damage that can happen to a MH if a tire blows—at just 60mph or so—I just cringe at this post and can't help but to think of what that dolly would be doing back there if that was to happen. But that's just me. Not judging you, just worried for you.

Safe travels my friend, easy does it.

Here's a recent post of a front left steer blowout at 64mph and he wasn't pulling anything:
http://www.irv2.com/forums/f258/our-...ut-356257.html

ahicks · 11-26-2017, 06:09 AM

I doubt seriously the 55mph speed rating on the dolly was based on tire performance. There are other factors to be considered, like the towing laws in various states for instance.

As mentioned, the max rating on the tire sidewall represents the tire's maximum performance. If you are not actually at maximum load, you do not need to run maximum pressure. In most cases, running a light load with tires at maximum pressure will rattle your brains out. That unnecessary road vibration is also hard on dolly components, like fender brackets, ramps, even license plates!

My best guess, without weighing the dolly when loaded, and assuming the new tires are at least as capable as the originals, the original OEM suggested 50psi should work fine.

Weighing the loaded dolly would be on my short list though. My experience has taught me you don't want more pressure than necessary, plus a minor safety factor, for maximum performance, and ride.

mrsportys · 11-26-2017, 07:13 AM

Found the answer on the Goodyear tire inflation site. At first glance for “ trailer” tires the max psi is 50. BUT a specific chart for the Goodyear endurance tire actually puts pressure to be used at a speed rating of D (to 85 mph! Not that I’d do that) and 65 psi as this tire has stronger side walls for “ downward” pressure in the tires from a tow dolly.
Problem solved!
Thanks to everyone

alank · 11-26-2017, 08:05 AM

So what's your final decision for pressure? Sort of sounds like you're thinking about 65 psi, and at that pressure I can assure you that you will be overinflated for the weight you will be carrying.

mrsportys · 11-27-2017, 08:56 AM

Quote:

Originally Posted by marjoa

Well Mr sporty pants....when I started reading your post I immediately started to cringe. I thought, here's a guy that has a 55mph rated dolly and tires and he goes 65 to 70mph on that. Now he's got 75mph rated tires so in his mind he's probably thinking he can safety go 75 or 80. With all the video's, pictures and other posts I've seen of the damage that can happen to a MH if a tire blows—at just 60mph or so—I just cringe at this post and can't help but to think of what that dolly would be doing back there if that was to happen. But that's just me. Not judging you, just worried for you.

Safe travels my friend, easy does it.

Here's a recent post of a front left steer blowout at 64mph and he wasn't pulling anything:
http://www.irv2.com/forums/f258/our-...ut-356257.html

That’s mr sporty pants to you! ��
I own the best dolly made, Demco ss. I would guess all tow Dolly’s would suggest you do not travel above 55mph.
Look at any I haul. Right on their fenders for towing it says 45-55mph max.
I would think it’s because trailer tires like those on towed vehicle, even 5th wheel trailers for the majority of cases have no name tires on them.
I decided to purchase a Goodyear tire ( and it cost double in price) that has 8 plies vs 6 , radial, a higher spend rating D vs C ( not for speed but for peace of mind when I am doing 65mph)

mrsportys · 11-27-2017, 09:07 AM

Quote:

Originally Posted by alank

So what's your final decision for pressure? Sort of sounds like you're thinking about 65 psi, and at that pressure I can assure you that you will be overinflated for the weight you will be carrying.

Going with the 65 psi, why? ( and I can’t seem to find now) Goodyear endurance trailer tire made specifically for 65psi with higher load rating ( 2040 per tire)
Now , you ask yourself why that’s only 4080 but that in the front of the dolly not the total load.
I guess I would have anyone using a tow dolly ( not pulling a car on 4 tires down) to look up the tires and see what their load rating is and what it actually can hold.
Hey, that’s why I’m here “ to eliminate a mistake before it happens”.

ahicks · 11-28-2017, 06:51 AM

You're getting the cart before the horse. The focus should be setting up (determining proper air pressure) for what your actual load is, not the max weight the tires are capable of.

Why would you set the dolly op for 4080 lbs if you're likely carrying less than 3000?

Your current logic would have you running the motor home tires at the max inflation shown on the sidewalls. We know that's not correct, right? The proper pressure is determined by the weight of the coach (without exceeding the pressure shown on the sidewall). That's exactly what we're talking about here!

Gary RVRoamer · 11-29-2017, 07:08 AM

Gotta agree with ahicks. Installing a tire with an increased load rating was probably a waste of money, but it apparently gave mrsportys some peace of mind.

The loading on the tire didn't change, cause the dolly and the Toyota still weigh the same. And since the new tire is the same physical size (205/75R14), the psi needed to carry that load didn't change either. The new tire could carry a higher load, but it won't unless a heavier car is placed on the dolly. So, the psi that was suitable before is still suitable with the new tire, as a look at thew tire load-inflation tables will show. Without an actual weight we can only guess, but if 50 psi was good before, it's still good now.

The Demco SS weighs about 600 lbs empty and is rated for a GVWR of 3500. That's the weight the dolly carries, not the entire weight of the car, much of which rides on the car rear axle. So the dolly tires see a max load of 3500 lbs, though I doubt the front of that Toyota pushes it that high. According to the GY tables, a load of 3500 lbs is a 50 psi load for a 205/75R15 tire, i.e. 2 tires @ 1760 lbs each.

The 55 mph dolly speed rating is below the speed rating of either tire. It's probably based on legal liability considerations rather than engineering, but that's another discussion. We already know that mrsportys ignores it.