Big Tires pulling Small tires.

[SweetLou]

A friend of mine asked me a question that I could not answer about his tires and towing. He has a small trailer weighing about 300 lbs unloaded and can carry up to 1000lbs total. Now the trailer has 13 inch wheels on it and his truck is a Dodge with 17 inch wheels. If he is going 60 mph, how fast do you suppose his 13 inch wheels are going? I suspect he means revolutions but you get it. He wasn't sure he could go that fast or faster in fear of burning up the trailer bearings. I really could not answer his question other than to say get them greased with good grease and try it out. Stop every 10-20 miles and see how warm they get. Of course I told him to put some weight in it as well to simulate the trip load and see. Anyone else know how to answer him?

[SweetLou]

valhalla360 wrote:

time2roll wrote:
CA speed limit is 55 mph for all vehicles towing.

So it's perfectly safe to run 70mph in Nevada but cross the state line and suddenly, it's dangerous? This is a political rule that has nothing to do with the tire speed rating.

Pull the model and look up the speed rating.

There is always someone in the bunch. They write more tickets.

[valhalla360]

time2roll wrote:
CA speed limit is 55 mph for all vehicles towing.

So it's perfectly safe to run 70mph in Nevada but cross the state line and suddenly, it's dangerous? This is a political rule that has nothing to do with the tire speed rating.

Pull the model and look up the speed rating.

[JRscooby]

NRALIFR wrote:

SweetLou wrote:
So the tire spins 1.3 times faster but we really don't know the speed of those small tires? Can we say 1.3 times faster than the truck, or 78 mph?

No, you can’t.

That would be nothing more than a variation of the trick question: “Which weighs more, a pound of feathers, or a pound of lead?”

The tires spin at a higher RPM, but the MPH is the exact same as the truck pulling it. :S

:):)

A track loader is moving 8 MPH. How fast is the pad on the ground moving?

[theoldwizard1]

Bottom line. Re-pack those bearings regularly !

[NRALIFR]

SweetLou wrote:
So the tire spins 1.3 times faster but we really don't know the speed of those small tires? Can we say 1.3 times faster than the truck, or 78 mph?

No, you can’t.

That would be nothing more than a variation of the trick question: “Which weighs more, a pound of feathers, or a pound of lead?”

The tires spin at a higher RPM, but the MPH is the exact same as the truck pulling it. :S

:):)

[time2roll]

CA speed limit is 55 mph for all vehicles towing.

[SweetLou]

Fisherman wrote:
I wonder if it's safe to ram food in as fast using a salad fork vice a regular fork.

Try it out and report back

[Fisherman]

I wonder if it's safe to ram food in as fast using a salad fork vice a regular fork.

[SweetLou]

Actually his old trailer is an old U-haul but he says it doesn't say that 45 mph rule anywhere. The tires on it are new and for a car since he really doesn't weigh it down any. The tire brand and specs say 937 lbs at max pressure which I don't know what that is. So the tire spins 1.3 times faster but we really don't know the speed of those small tires? Can we say 1.3 times faster than the truck, or 78 mph?

[rlw999]

JRscooby wrote:

As for the " some utility trailers with a 45 mph max towing speed." I have only seen that on rental trailers. I don't think it has much to do with the construction of the trailer, but more to do with reducing the chance of liability. The rental companies understand the average motorist has no understanding about how a trailer will effect how the TV handles.

No doubt it's a liability issue, but it's not just rental trailers, seems to be the cheap ones like the ones sold at Harbor Freight or Northern Tool:

https://www.y2-supply.com/products/new-ultra-tow-5ft-x-8ft-aluminum-utility-trailer-kit-1715-lb-load...

https://www.northerntool.com/shop/tools/product_200612544_200612544

https://manuals.harborfreight.com/manuals/62000-62999/62647.pdf

[time2roll]

Does no-one recall 13" wheels where very common on cars a couple decades ago? Yes those tires can go on the highway with no issues.

[mooky_stinks]

Many open snowmobile trailers have 8-10” rims and tires that have 20” diameters. Highway towing is NOT an issue. In fact etrailer has tires that are rated for 81mph. As long as the bearings have the proper maintenance and the axle isn’t overloaded there’s nothing to be concerned about. Plenty of cars had 13” wheels 20 years ago.

[JRscooby]

rlw999 wrote:

SweetLou wrote:
A friend of mine asked me a question that I could not answer about his tires and towing. He has a small trailer weighing about 300 lbs unloaded and can carry up to 1000lbs total. Now the trailer has 13 inch wheels on it and his truck is a Dodge with 17 inch wheels. If he is going 60 mph, how fast do you suppose his 13 inch wheels are going? I suspect he means revolutions but you get it. He wasn't sure he could go that fast or faster in fear of burning up the trailer bearings. I really could not answer his question other than to say get them greased with good grease and try it out. Stop every 10-20 miles and see how warm they get. Of course I told him to put some weight in it as well to simulate the trip load and see. Anyone else know how to answer him?

265/70R17 tires have a diameter of around 31 inches, 185/80R13 have a diameter of around 24".

Circumference is diameter * pi, or 97" for the 17" tires and 75" for the 13" tires, so the 13" tires will be spinning 97 divided by 75, or 1.3 times faster.

At 60mph, the 17" tire will be spinning at around 650rpm, and the 13" will be spinning around 850 rpm.

But I'm not sure that really helps answer your question since I haven't seen an axle rated in RPM or max speed, just weight limit. As long as it's rated for road use (and isn't, say, an axle meant for a garden tractor), I'd think it'll be ok at normal street speeds... but I've seen some utility trailers with a 45 mph max towing speed.

The little wheels spin faster, no doubt. But the bearings are designed to let the wheels spin, so if serviced properly likely not a issue. The tires are likely rated for lower speed, so that will be a issue.
As for the " some utility trailers with a 45 mph max towing speed." I have only seen that on rental trailers. I don't think it has much to do with the construction of the trailer, but more to do with reducing the chance of liability. The rental companies understand the average motorist has no understanding about how a trailer will effect how the TV handles.

[rlw999]

SweetLou wrote:
A friend of mine asked me a question that I could not answer about his tires and towing. He has a small trailer weighing about 300 lbs unloaded and can carry up to 1000lbs total. Now the trailer has 13 inch wheels on it and his truck is a Dodge with 17 inch wheels. If he is going 60 mph, how fast do you suppose his 13 inch wheels are going? I suspect he means revolutions but you get it. He wasn't sure he could go that fast or faster in fear of burning up the trailer bearings. I really could not answer his question other than to say get them greased with good grease and try it out. Stop every 10-20 miles and see how warm they get. Of course I told him to put some weight in it as well to simulate the trip load and see. Anyone else know how to answer him?

265/70R17 tires have a diameter of around 31 inches, 185/80R13 have a diameter of around 24".

Circumference is diameter * pi, or 97" for the 17" tires and 75" for the 13" tires, so the 13" tires will be spinning 97 divided by 75, or 1.3 times faster.

At 60mph, the 17" tire will be spinning at around 650rpm, and the 13" will be spinning around 850 rpm.

But I'm not sure that really helps answer your question since I haven't seen an axle rated in RPM or max speed, just weight limit. As long as it's rated for road use (and isn't, say, an axle meant for a garden tractor), I'd think it'll be ok at normal street speeds... but I've seen some utility trailers with a 45 mph max towing speed.