Effect of Tire Load Rating on Aired Down Performance?

[CopaTJ99]

Torn between 33x10.50R15/C versus 255/85R16/D. Inclining towards latter because of its slightly larger diameter. Thus my question follows:

Can someone articulate the difference in performance (ride quality and traction) between a load rating "C" and "D"? I was told that when aired down, the "D" will not conform to obstacles due to its stiffer carcass as well as "C" and thus less traction. Is "D" really a harsher ride on the trail? Any other difference or advantage of one over the other?

Anthony

[lancetkenyon]

In a very minute amount, the "D" rated tire will not deflect quite as much. But since the Jeep weighs less than 4K lbs, there is really no need to go with a "D" load range tire. I don't know if you would ever notice the difference between the 2. Besides, what rim size do you have, you stated 2 different rim sizes on yourt choices of tires. And are you limited to those 2 sizes?

[CopaTJ99]

I currently have the stock 15x7 Eccos with BFG AT 31x10.50. Planning to go 33x10.50R15 or 255/85R16. I anticipate that I will need to get new wheels either way. Likely steel rockcrawlers 15' or 16's.

[p14175]

I used D rated BFGs (285/75r16s) on my ZJ (3500#?) and they were lousy until they were almost worn out. What I mean by lousy wasn't the ride quality. The old ZJ had a very soft (flexible) suspension which ate up the bumps. The tires were lousy in the traction department. The sidewalls were too stiff for the weight of the vehicle and the tires always felt like they were floating instead of grabbing like they should have doing.

One big mistake I made was putting them on right before a trip to the Rubicon Trail. I should have kept the 33x9.50r15s for that trip. While I never needed a strap or winch assist on that trail, I had to power through obstacles that I would have rather finessed my way through. At the end of the trail I was already thinking about what to replace them with. I found that Yokohama makes a C rated 285/75r16 MT that fit the bill nicely.

There are several really good tire forums on the internet. You might want to post your question on one of those as well.

Good luck!

[lancetkenyon]

With a 33-10.50, your 15x7 will be fine. Go for the C load tires.

[desertfabmotors]

Load range C is a 6 ply and D is a 8 ply

The 8 ply will have a stiffer sidewall so you will need to air down more.

[lancetkenyon]

I also assume you are talking about radials. Radials will flex much better than bias ply, but bias are much tougher. And with radials, the 6 or 8 ply is not in the sidewalls, only the tread area. Sidewalls are usually 2 or 3 ply. That is why the radials flex better. Bias carry the ply through the sidewalls.

[desertfabmotors]

I And with radials, the 6 or 8 ply is not in the sidewalls, only the tread area. .

The sidewalls may have the same ply ratings but there is a difference in the structure of the sidewalls which make them stiffer. this is why the load rating is higher.

[lancetkenyon]

The sidewalls may have the same ply ratings but there is a difference in the structure of the sidewalls which make them stiffer. this is why the load rating is higher.

That is good to know. Who makes the radials with 8 ply sidewalls that are not an E load range? I know BFG and GY have 3 ply sidewalls on their MTs.

[desertfabmotors]

That is good to know. Who makes the radials with 8 ply sidewalls that are not an E load range? I know BFG and GY have 3 ply sidewalls on their MTs.


You can have a LR C & LR D both with 4 ply sidewalls and the LR D will have a stiffer sidewall.

There are a difference in the ply's design. The new cooper STT have a new ply design that is stronger than older design but have the same ply rating.

Make sense?

[lancetkenyon]

You can have a LR C & LR D both with 4 ply sidewalls and the LR D will have a stiffer sidewall.

There are a difference in the ply's design. The new cooper STT have a new ply design that is stronger than older design but have the same ply rating.

Make sense?

Now I got you. I went back and reread you earlier post. I thought you were saying there was a radial with 6 or 8 ply SIDEWALLS....not rating.:rolleyes: Stupid me.:o

[ob1jeeper]

FWIW: "ply rating" is a hold-over from the days when adding plys was the main/only way to add load carrying capacity to a tire carcass design...

Modern tire technology, including the advent of radial tires, and the uses of the myriad of hi-tech ply materials that are now available, allow a tire with two to three plys to be rated for the same load carrying capacity of what was once only possible with a 6-plus ply rating...

Similarly load range was instituted as a rating system to try to overcome the ply ratings shortcomings when the same load capacity became possible with fewer plys...

IF you are talking about DOT rated tires (required for tires sold for use on public roadways) THE best load rating information is on the sidewall of the tire, where you will find the max rated loaded capacity of the tire when aired to the max rated pressure... What this information tells you is that in order for the tire to be able to safely loaded to that max rating, the tire pressure needs to be set at that pressure, or ... it will fail prematurely... and the typical failure when overloading the tire is no different than runing too low of tire pressure at highway speeds... IE: Internal to the tire carcass material heat damage as a result of "working" (or bending) the sidewalls ... Just like bending a wire rapidly...;)

HTH...:);)