Convert ST tires to LT tires

[Red_wing]

Hi everyone

How do you convert ST tires size to LT tires size? For example 235/80R/16 load range E to a light truck tire size.

[MrVan]

Sledge Hammer wrote:
I just got rid of the 235/80 16E ST tires my '13 Fuzion 315 came with and changed to Goodyear 235/85 16G LT tires and run them at the full 110 lbs. air pressure. I have not noticed any ride issues and appreciate the increased load capacity. It seemed like a waste to throw away what were basically new tires, but I have much greater peace of mind with the Goodyear G rated tires.

Were the original rims rated for 110 lbs?

[Sledge_Hammer]

I just got rid of the 235/80 16E ST tires my '13 Fuzion 315 came with and changed to Goodyear 235/85 16G LT tires and run them at the full 110 lbs. air pressure. I have not noticed any ride issues and appreciate the increased load capacity. It seemed like a waste to throw away what were basically new tires, but I have much greater peace of mind with the Goodyear G rated tires.

[aruba5er]

I changed to LT tires and I really don't like the ride. Towing got harsher and sometimes I worry about the side loads of the wheel bearings as the lt's don't flex like the old ST's I have tweaked the pressure and now run around #70 and the ride is much better. I do like the fact the tread seems to be thicker and more resistant to road hazard (my perception) but if I ever need tires again I will probably go with Maxis.

[Atom_Ant]

Confused yet?

[Like2Travel]

Take a look at this linky. It can be used to check tire diameters. You might like to be sure any tire change will fit up under your 5er and have room to put your chocks in between wheels.

[hoopers]

Replacing ST tires with LT tires can be a confusing and daunting task, especially if you have never done it before. There are hundreds of threads on this 4m alone about the subject. It really depends on the weight each of your trailer tires is expected to carry.

Typically, the same size ST tire will be rated higher than a corresponding LT tire. However, there are some Goodyear tires that buck that trend. Most ST tires are specified at 62 MPH max, whereas LT tires are specified at higher speeds. Personally, I think this is one of the reasons for so many ST tire failures...you should go slow (< 62 mph) on them at all times.

I know many people simply buy a top end LT tire, and call it good. But many others, including me, made the decision to make sure each tire was specified to carry the weight placed on it.

Here is one link that helped me a lot, and has been posted on this 4m many times before:

Linky

[JIMNLIN]

Red wing wrote:
Hi everyone

How do you convert ST tires size to LT tires size? For example 235/80R/16 load range E to a light truck tire size.

What we actually do is choose a 'recommended' LT tire with enough capacity for the trailers axle ratings and that will fit under the wheel well.
As some have said a LT E in several USA brands with 3042 lbs capacity work great on 6k axles.

If your trailer has 7k axles then choices are limited to the Goodyear G614 or the Sailun S637 load range G at 3750 lb capacity and 110 psi.

Some with the heavier units upgrade to the 17.5" wheels and commercial grade LT tires.

One poster suggests we only give brand names with unacceptable tire sizes on this forum or only the trailer manufacturer can help and their the only source of replacement recommendations. Simply not the case.
Most experienced trailer owners know better than to call the trailer mfg and get the same OEM bad tire recommendation they put on their trailer to begin with plus some trailer mfg are not in production anymore. There is no requirement to contact any trailer mfg for replacing tires.

Your best source for a recommendation is a forum (and many others) like this with hundreds of trailer owners who have been through the tire replacement process for 30-40 years.

Now if we knew some specs such as your axle ratings/trailers GVWR we can give you some excellent tire choices.

[cpaulsen]

I replaced my ST235/80/R16's with LT245/75/R16 without any problems.

[FastEagle]

Red wing wrote:
Hi everyone

How do you convert ST tires size to LT tires size? For example 235/80R/16 load range E to a light truck tire size.

Unfortunately almost all of the ST tires have unique size and load capacity specifications. Unlike automotive tires, RV trailer tires - any design - do not have T&RA replacement recommendation charts. So, solicited recommendations will be heavily biased with brand names and unacceptable sizes..

When we do find a valid comparison in size with another tire design we see the vast differences between tire designs/specifications.

The ST235/85R16E has an average diameter of 31.7" on 6.0" wide rims. It will have a tread depth of 10/32". It's maximum load capacity at 80 psi is 3640#.

The LT235/85R16E has an average diameter (on 6.5" wide rims) of 32". It's normal tread depth is 15/32". It's Maximum load capacity at 80 psi is 3042#.

The ST235/80R16E has no acceptable size or load capacity replacement. You should ask your trailer's manufacturer or the tire's manufacturer about replacement recommendations. That's what your owner's manual will recommend.

Because your certification label only depicts the tire size and load range, any of the load ranges - 3420 - 3500 - 3520 - become acceptable replacements.

FastEagle

[FastEagle]

mileshuff wrote:


The LT tires typically are underrated by 20% to allow a safety margin.

Can you provide a reference for that statement? I'd like to read it.

FastEagle

[ken_white]

Red wing wrote:
Hi everyone

How do you convert ST tires size to LT tires size? For example 235/80R/16 load range E to a light truck tire size.

The 235 number is the width in millimeters. There are 25.4mm per inch, so 235mm*(1in/25.4mm) = 9.25"

The 80 number is the aspect ratio (sidewall height/width) which represents 0.8 ratio. So 235mm*0.8 = 188mm.

Converting the 188mm height to inches 188mm*(1"/25.4mm) = 7.4".

Since the side wall height has a top and bottom, the overall sidewall height is 14.8".

A 16" wheel + 14.8" of sidewall height means the tire is 30.8" tall unloaded.

So, the LT could be a 31" x 9" x 16" tire, or rounded some other way...

[pronstar]

waltbennett wrote:
Truck tires have more flexible side walls as they may be on steerable wheels, trailer tires have stiffer sidewalls as they won't be steering.

If comparing LT to ST...then no, this isn't really true.

[mileshuff]

ol Bombero-JC wrote:
If it's inadequate - go to a different size, ex: 245/75 (which will be the same diameter, but 1" wider).~

245/75's are about 1/4" wider than the 235/80's. However, it most likely is less. The measuring rim used for manufacture specs on the LT245/75 is often 7" while on the ST235/80's it is 6.5". Thus if you mount a 245/75 on a 6.5" rim you'll be less than the 1/4" spec difference.

[time2roll]

Use the load capacity rating. I suggest you buy tires that cover the entire GVWR of the trailer. Check wheel pressure rating before you increase pressure much.