Taller sidewall tires -verses -Shorter sidewall tires

[deepNdirt]

I recently changed out the tires on my 16 tf. trailer, The previous tires ( car tires )had good tread although were old and showing dry-rot cracking, They no longer look safe to be on the roadway,...... My son works at a Tire/Battery shop and brought me some good take-offs,... Now before we get into a discussion that I should be running an actual "Trailer Tires" .... we all know our trailer don't get used as much as we would like to ...in order to justify a purchase of NEW ones, ( at least for me ) So I choose to get a good Used set every 4/5 years or when needed and pay a minimum cost, usually around 100 for a set,........................
Now for the question: The old tires size 235/75/15 ( good year radial ) had a large sidewall and when under a 2-ton load and with the tire pressure at 35psi the tires would smile,
Now after changing to a shorter 215/65/15 tire size, The side walls are of course shorter but yet much firmer tire with still under the same load and tire pressure, This size tire does not flex or smile, But is this a good Thing? when comparing the two size tires under the same load and air pressure which is in fact the more suitable tire to use? incidentally... with running the shorter tire it does give an advantage of lowering the trailer making it easier to drive up onto, But still I cannot help but to think that more sidewall would be better..... any thoughts or expertize on this subject?

 

[Markcuda]

You may experience a little firmer ride with the shorter tires.
But so what.

 

[zzvyb6]

I recently changed out the tires on my 16 tf. trailer, The previous tires ( car tires )had good tread although were old and showing dry-rot cracking, They no longer look safe to be on the roadway,...... My son works at a Tire/Battery shop and brought me some good take-offs,... Now before we get into a discussion that I should be running an actual "Trailer Tires" .... we all know our trailer don't get used as much as we would like to ...in order to justify a purchase of NEW ones, ( at least for me ) So I choose to get a good Used set every 4/5 years or when needed and pay a minimum cost, usually around 100 for a set,........................
Now for the question: The old tires size 235/75/15 ( good year radial ) had a large sidewall and when under a 2-ton load and with the tire pressure at 35psi the tires would smile,
Now after changing to a shorter 215/65/15 tire size, The side walls are of course shorter but yet much firmer tire with still under the same load and tire pressure, This size tire does not flex or smile, But is this a good Thing? when comparing the two size tires under the same load and air pressure which is in fact the more suitable tire to use? incidentally... with running the shorter tire it does give an advantage of lowering the trailer making it easier to drive up onto, But still I cannot help but to think that more sidewall would be better..... any thoughts or expertize on this subject?

I suppose these are P235/75-R15 vs P215/65-R15 (both P-Metric Radial tires). The P235s could be LL (light load) SL (standard load) or XL (extra load) designation. Same for the 215's. You didn't say. An SL 235 has a rated load capacity of 2028 lbs on car use and the 215's have a rated load capacity of 1521 lbs, both at 35 psi. Look at the sidewall label(s) to see what you really have. Also look at how many plys on the tread and sidewall. The sidewall flex difference is probably due to the sidewall construction type as well as the aspect ratio (75 vs 65). If you are not overloaded, then there should not be a problem. Just make sure you have air pressures checked. Occasional use trailers are notorious for flats and blowouts because owners let thm sit for a while and never kick the tires (or the wiring, either).

 

[mikehaugen]

I am not sure what kind of weight you are putting on it, but any tire rated for 35 psi has to be a light duty tire. As stated before, check the sidewall for max weight at given pressure, and make sure it is capable of what you are doing with it and it should be fine. I always run mine at max rated pressure.

 

[Diamondpilot]

I agree with the guys. If you are not going to spring for trailer tires atleast get some load range C Truck Tires and air them to 55psi.

Chris

 

[deepNdirt]

The 215.65 tires reads Max air 51psi and standard load with 2 ply sidewall,
the 235.75 reads max air 35psi standard load 2 ply sidewall,
The heaviest thing I load is My cut tractor rated 2500 lbs and a couple implements that would total probably another 800 to 1000 lbs, plus the weight of the trailer itself, as I stated earlier around 4000 lbs./ 2 tons give or take,
if each tire is rated estimated at 1500 lbs load this should put it capable of around 6000 lbs max load, I was just curious about which of the 2 size tires have a stronger sidewall? while the larger tire and sidewall seems to smile or flatten out more under the same load as the shorter sidewall, the shorter sidewall seems not to flatten out at all,

 

[JDgreen227]

The 215.65 tires reads Max air 51psi and standard load with 2 ply sidewall,
the 235.75 reads max air 35psi standard load 2 ply sidewall,
The heaviest thing I load is My cut tractor rated 2500 lbs and a couple implements that would total probably another 800 to 1000 lbs, plus the weight of the trailer itself, as I stated earlier around 4000 lbs./ 2 tons give or take,
if each tire is rated estimated at 1500 lbs load this should put it capable of around 6000 lbs max load, I was just curious about which of the 2 size tires have a stronger sidewall? while the larger tire and sidewall seems to smile or flatten out more under the same load as the shorter sidewall, the shorter sidewall seems not to flatten out at all,

I can identify with your situation about not wanting to spend megabucks on special tires, given your limited use of the trailer. To me, a shorter sidewall would be better as it would flex less, however that would give less cushioning than a taller sidewall. Less flex means less heat build up, right? And IMO a 2-ply sidewall is a 2-ply sidewall, no matter what size the tire is.

 

[deepNdirt]

Another thing that occurred to me, Perhaps the width size of the rims contributes to the effect of the sidewalls,
I believe the width of the wheel is 6 1/2...... so if a 235.75 tire is roughly 8.5" wide, this means it would be 2 inches wider then the wheel and will result in a rolled over sidewall, Right! ..... and if the 215.65 is... will say 7" wide then this is almost an exact fit to the width of a 6.5 wheel, and this size tire will stand more upright and firm on its sidewall, Now if were to mount the 235.75 onto a 8" wide wheel then it too would be more suitable to the wheel and perhaps become firmer and stand more upright, Right!

 

[joe t]

I'm not a tire expert but I've noticed bigger tires offer a higher max lb rating in different load rated tires.


So for example in a couple tires I've used, the 315/70/17 35x12.50 D rated tire has 3195lbs rating and a 265/70/17 32x10 inch E rated tire has the same 3195lbs rating. D rating is lower than E but they say they will carry the same weight. One thing about the bigger D rated tire is that I notice it sags much more under the same load.


On my utility trailer with 3500lb axles I run some 235/75/15s like you did, they are C rated and advertise something like 2300lbs on the sidewall. I keep them aired to the max and don't worry, they surpass the axle ratings by a good bit.


Long story short, I'd check the sidewall and find the max load and air pressure to acheive that. To get max load rating you need to put the max air in them.

Also with max air pressure if you loose some pressure from just sitting up or weather you won't be as likely to fall below the minimal pressure which is kinda convienent when you are in a hurry to hook and go safely.



Also, also I have always used auto tires on trailers and haven't had problems. I've read the bias ply trailer tires are designed to not dry rot and that was the only benefit I remember reading about them. I could be wrong though and the whole world is falling down around me every time I pull one of my trailers since I use the wrong tires.