Different size trailer tires

[wh]

I have a trailer with trailer house axles. We've mixed 7-14.5 and 8-14.5 for the past 40 years since my dad built the trailer. But we usually try to keep the tires on an axle the same size side to side. I wouldn't recommend mixing tires with more than an inch or so difference in height on an axle. If you had a big difference in height from 1 axle to the other, but the tires on each axle were the same size side to side it wouldn't make any difference. Axles with 1 tire taller than the other tend to pull to the side with the shorter tire. Not a big deal at low speeds but more noticeable at higher speeds.

You said it well. That was problem i described above.

 

[BarnyardEngineering]

It's a spare. All it needs to do is get you home, which it will. You might have to limp it home, but you probably won't even notice a difference. I think our cattle trailer had three different size tires on it at any given time. Dad would put whatever janky old 15" car tire on it that he had kicking around. I think at an given time it could have a 205/75R15, 215/75R15, 235/75R15 and an H78-15 bias ply. Dang thing looked like Bill the Cat from the side.

 

[wh]

huh ?

Geometry at its best. Larger diameter will gain several inches per revolution pulling that side of trailer with it. Then trailer will jerk or wiggle or whatever to correct its self. As a spare no problem. As a full time tire no way.

 

[sotxbill]

You asking, "a 16 inch tire for a spare next to a 15 inch tire" implies you have a dual tire axle arrangement (two tires next to each other). A 16 beside a 15 on a dual tire set, only as a last resort. in my opinion. A 16" tire ahead of, or behind, a 15" tire on a multi-axle single tire set up, with equalizers, not a big issue. So, what it the axle and tire arrangement you are asking about?

Ive not seen 15 inch duals.... so far... but there's still time.

 

[Jim.ME]

Ive not seen 15 inch duals.... so far... but there's still time.

Maybe not, but 37 chief posted "If I use a 16 inch tire for a spare next to a 15 inch tire is that a problem." Next to implies the tires are beside each other, or dual tires to me. I figured it was more likely he meant in front of or behind on a different axle but wanted to be sure. I have seen many things over the years I never saw before so better to clarify than rule something out.

 

[Jim.ME]

Geometry at its best. Larger diameter will gain several inches per revolution pulling that side of trailer with it. Then trailer will jerk or wiggle or whatever to correct its self. As a spare no problem. As a full time tire no way.

Agreed the larger tire will cover several inches more of distance per revolution than the smaller tire. However, if the trailer moves say 1000 feet, each tire is free rolling on a separate axle, the large tire will make fewer revolutions to travel that 1000 feet than the smaller tires.

MATH:

ST205/75R15 at 7.1 ft. circumference will turn 743.66 revolutions in one mile on a free spinning axle hub.

ST205/75R16 at 7.35 ft. circumference will turn 718.36 revolutions in one mile on a free spinning axle hub.

The difference in diameters is self-corrected by the number of revolutions (speed) each of the tires has to turn to cover the same distance.

Edited to add the calculations for per mile revolutions.

 

[Mcrafty1]

I would think using it to get you home or to a tire shop would be fine, if you run them together very far one is going to make the other one wear funny do to the difference in circumference. One making less revolutions per mile than the other.

 

[Scott 730]

Geometry at its best. Larger diameter will gain several inches per revolution pulling that side of trailer with it. Then trailer will jerk or wiggle or whatever to correct its self. As a spare no problem. As a full time tire no way.

?? Help me understand this rationale. Each tire is on it's own axle, so who cares if one spins faster than the one on the other axle.

 

[JMOR]

?? Help me understand this rationale. Each tire is on it's own axle, so who cares if one spins faster than the one on the other axle.

wh saw something, drew a conclusion and he is sticking with it come H or high water.

 

[Russ from MN]

Ever look at big trucks that have air-lift axles? The tires on the lifted axles are usually smaller that the driven ones. I would think the most important place to not mix different dimeter tires is on duals, where they are on the same hub, and driven axles.

 

[wh]

wh saw something, drew a conclusion and he is sticking with it come H or high water.

Straight from etrailer information about tires. You do you. As a spare for short distance there is no problem. Permanent running you need all tires on same axle the same size.

 

[BarnyardEngineering]

I'm not saying the tire wasn't your problem. I am saying the size wasn't your problem.

I agree. The reason the tire was 1-1/2" larger is because it had broken cords/bands, and it was no doubt egg-shaped, causing the trailer to bounce all over the place. I've had trailer tires do that.

 

[wh]

I agree. The reason the tire was 1-1/2" larger is because it had broken cords/bands, and it was no doubt egg-shaped, causing the trailer to bounce all over the place. I've had trailer tires do that.

Tire was fine. Used it later on another trailer. From then on we measured and matched tires. See the explanation above copied from etrailer online. I always liked for a trailer to pull straight. Told the ones ordering from us if it did not pull straight at 75 mph to bring it back and we would figure it out. Only one to ever come back had the mismatched tires. You can run wooden wheels and tires if you want to. I always want trailer pulling smooth enough that i do not know i am pulling a trailer. And just for info my high school welding students built an average of 10 trailers a year. Ranging in size from simple 5 x 8 to 8 x 24 tri-axle goosenecks. Used mobile home axles to factory trailer axles. Just depended on planned use for trailer.

 

[Mule Meat]

Interesting.. I pull my trailer 20 miles.
One side will travel 20 miles while the other travels 25 1/4...

 

[sotxbill]

Dad always called those 12 inch tires.... "100 mile per hour tires"

 

[Scott 730]

Sorry, but I'm not buying this. As long as the trailer axles are in alignment, what difference can it possibly make if the tires are not all turning at the same RPM? They are all free to do their own thing on their respective axle. Should have no bearing on the tire in front of, or behind, or on the other side of the axle.

 

[wh]

Sorry, but I'm not buying this. As long as the trailer axles are in alignment, what difference can it possibly make if the tires are not all turning at the same RPM? They are all free to do their own thing on their respective axle. Should have no bearing on the tire in front of, or behind, or on the other side of the axle.

take an axle. Put a 1 1/2 to 2 inch taller tire on one Side. Mount smaller tire on other. Stand in center and push axle away. Watch it run to the smaller side.

 

[ss55]

Without knowing the two tire sizes there is no way to determine if the two diameters are close or not.

Maybe just go ahead and mount the odd size tire on an axle and test how well the trailer pulls, empty first and then loaded. It is better to know ahead of time if it will cause any problems rather than wait until you have a flat out on the road and then find out it will not work at the worst possible time.

 

[BarnyardEngineering]

Tire was fine. Used it later on another trailer. From then on we measured and matched tires. See the explanation above copied from etrailer online. I always liked for a trailer to pull straight. Told the ones ordering from us if it did not pull straight at 75 mph to bring it back and we would figure it out. Only one to ever come back had the mismatched tires. You can run wooden wheels and tires if you want to. I always want trailer pulling smooth enough that i do not know i am pulling a trailer. And just for info my high school welding students built an average of 10 trailers a year. Ranging in size from simple 5 x 8 to 8 x 24 tri-axle goosenecks. Used mobile home axles to factory trailer axles. Just depended on planned use for trailer.

The etrailer guy is full of baloney, but I'm done with this conversation. If it works for you, then it really doesn't matter who is right.

 

[JMOR]

I'm pretty sure that the worst thing that will happen is that your trailer speedometer may give incorrect indication of speed!