Tire speed

Trust me on this one OP - If the tire is rated for 65 mph it's good to go at 65 mph. The manufacturer has already taken into account the tires rpm's at 65 mph and designed it accordingly. It doesn't matter if it's a 6 inch tire or a 21 inch tire; the only thing that matters is it's speed rating (mph).

This post reminds me of an old joke: If a jackrabbit's front legs are moving at 75mph, what are the back legs doing? Hauling tail... (I cleaned up the joke..)

mph is mph

your truck is doing 65 so is your trailer

but your tall truck tires are turning at a slower RPM, than the smaller TT tires that have to turn higher RPM to cover the same driving distance

your confusing RPM with MPH they are too different things

the larger the wheel the lower the RPM, the smaller the wheel the faster the rpms for the same MPH of travel , rolling on the highway

both sets of tires are going 65 MPH, but the smaller set covers less road with each rotation, and has to rotate faster/more often, to maintain 65mph

Maybe you should also consider that the larger and heavier tires also need larger brakes.
Frank.

Jerry (the OP),

Wading through all the joking above ... I'm guessing that you have now figured out that the smaller the diameter of the tire, the more times it rotates per mile over the rotations of a larger diameter tire.

What this means is that smaller diameter tires are wearing faster at any average vehicle/trailer rate of travel than larger diameter tires. This faster spinning of a smaller diameter tire also generates more heat in the tire per mile.

Case in point, when my Brother-In-Law was shopping for a new small RV trailer I recommended that he get one both with double axles (for more safety in case one tire on one side should fail at speed) and large as possible diameter tires to minimize tread wear and tire degradation from heat.

I shake my head at all the tire life and reliability complaints that RV trailer owners post in the forums. It's no wonder this is going on .... just compare the little donut tires on many RV trailers - that are in many cases carrying a relatively high weight load - to the larger diameter and beefy looking tires on Class B and C motohomes that may be carrying similar weight loads. I have often wondered why trailer owners don't increase the diameter of their trailer tires at replacement time if the clearance is there to allow it.

Busdriver wrote:
Never saw this question asked, say your truck has 275/70/18 tires your trailer has 225/75/15 speed rated 65, if you’re truck is doing 65 how fast are your trailer tires going what I am getting on a tire speed conversion chart the trailer tires are going 76 mph

The speed conversion chart you are referring to is probably for use when changing tire and rim diameter sizes on a motor vehicle and is for determining the true speed of the vehicle in relation to the speedometer reading.

When putting larger tires on a motor vehicle the speedometer shows you going slower than you really are. When putting on smaller tires the speedometer shows you going faster than you are. The gear at the transmission for the speedometer would need to be changed to show the correct speed for the difference in tire diameter. That is what the conversion chart is showing.

Must be something to it. Because in my 45 years of towing trailers. I have not one time been able to out run the trailer. It is right behind me every time I look in the mirror

I'm going to work up the nerve to ask something here one day.. But in the mean time it sounded like he said his trailer is going 11mph faster than his truck. I'm shore that's not what he meant to say and yes smaller tires turn more RPM than large ones. Cant wait for spring.:)

I read OP's question a little differently.
Yes, he said speed but I took it more of question of RPM.

miles-per-hour is miles-per-hour regardless of tire size/circumference/width or what type of vehicle the tire is mounted on...

so the correct answer is, if the truck is doing 65mph on its 270/70-18 tires, the 225/75-15 tires on the trailer that is being towed along behind will be going 65mph also....