Wanting to change from STs to LTs..........

[Paulb1310]

We are the proud new owners of a 2007 K-Z Sportsman 5th wheel. The unit is in EXCELLENT shape for its age. This is our first (but likely won't be our last).

I have read numerous posts on the arguments of STs versus LTs. My conclusion is the I am going to replace the current tires/wheels with larger, more robust ones.

Here is what I currently have:
Tire: Load Max Radial
Tire Size: ST225/75R15
Overall diameter: 28.3"
Rim width range: 6-7"
Date Code: 614 0906 (waaaaay old!)
Wheels: Six bolt on 5.5" centers
Load rating for each tire: 2540 pounds
GVWR for trailer: 10,000 pounds

Here is what I want:
Tire: Michelin LTX A/T 2
Tire Size: LT245/75R16
Rim width range: 6.5-8"
Overall diameter: 30.5"

Wheel Choice #1: HiSpec Series 04
Wheel Size: 16x7
Wheel load rating: 3200
Offset: +5mm

Wheel Choice #2: HiSpec Series 05
Wheel Size: 16x6.5
Wheel load rating: 3580 pounds
Offset: 0mm

So, what have I considered so far?

1. Separation between current tires is 5.0". By using this size tire the separation would be 2.8". This would appear to be sufficient.

2. Currently there is 6" of suspension travel between the top of the tire and the floor of the 5th wheel. This would be reduced to 4.9". This, too, seems sufficient.

3. The passenger side shocks currently sit 3/4" away from the tire. This might be dicey with a bigger tire and wheel. If the tire is too close the options are to (a) put a spacer between the wheel and the hub with longer lug nuts or (b) move the shock to the other side of the axle (likely NOT a good option.)

4. The passenger side front tire is close to the fender. I could (a) trim off part of the fender or (b) install a brace underneath to push the fender our a few tenths of an inch or (c) a combination of (a) and (b).

5. The top of the tire to the bottom of the fender is 3.5". I don't know just how much more the bigger tires would protrude. Of course, the current tires don't have a problem with hitting the inside edge of the fender. I'm not sure if the bigger tires would have an issue or not.

So, what have I missed?


Thanks for your help!!

Paul.

[Me_Again]

gdweb wrote:
if your set on michelin ltx, have you considered the m/s2? about the same price, just a less aggressive tread.

The M/S2 has two much siping to be considered a good trailer tire. It also has breaks in the outer ribs, which is not the best for a trailer tire.

Chris

[gdweb]

if your set on michelin ltx, have you considered the m/s2? about the same price, just a less aggressive tread.

[bobx2]

Several E rated tires available in a 15" size. I upgraded to a set of E rated Carlisles 225-75-15. My 5th wheel grosses the same as yours at 9,999 lbs. Plenty of extra capacity for a safety margin now. Need to be sure your wheels are rated for 80 psi if you want the benefits from the E rating.

[bpounds]

Paulb1310 wrote:

I couldn't find an E rated tire in a 15" size. Am I missing something or are all the 15" tires limited to 2540 pounds?

ohiopicker wrote:
Maxxis has their 8008 tires in Load Range E in 15" size. They've held up great on my trailer.

I just ordered those Maxxis for my own trailer. Getting them mounted on Sat. Paid $104 each.

Powerking Towmaster also has that tire in an E. I wouldn't necessarily recommend them, although that's what came on my trailer in an LR-D, and they have been okay for almost 4 years and over 12k miles. I'm replacing them due to age and weather cracking. But they haven't blown up on me and my trailer is also 10k GVWR. So while I didn't buy Powerking again, and would not recommend that, it is an example of an ST tire holding up fine when running well below max rating. I think Maxxis will be a better tire.

The LR-E in that size has a 2,830lb rating.

[ohiopicker]

Maxxis has their 8008 tires in Load Range E in 15" size. They've held up great on my trailer.

[Paulb1310]

jimnlin wrote:
Excellent point for a highway trailer. Now if the OP goes off roading then that type tread will help tracking in mud/etc.
Tires for trailers need at least one solid rib in the center of the tread or both edges for best tracking/handling.

Well, we do plan on taking this trailer onto some backroads. That is one of the reasons we bought a smaller trailer. As a matter-of-fact, if we could have found one at 20 feet, that would be the one we purchased. We are wanting to do dry camping to get closer to nature for me and to the stars for my wife. lol

Me Again wrote:
I would install LT235/85R16E R250's on 6 or 6.5 zero offset wheels and deal with stocks as necessary. On trailers it is very important to have zero offset wheels centered on hub bearings. Just ask Titanium owners that got OEM axles and wheels that were not setup that way.

That is an interesting and important tidbit about the offset.

bpounds wrote:
I suspect you're throwing a lot of money at a problem that doesn't exist. At most you could consider going up to an E rated tire in the same size, and probably only pay around $25 total extra for all four over the D rated.

I couldn't find an E rated tire in a 15" size. Am I missing something or are all the 15" tires limited to 2540 pounds?

[bpounds]

My question would be, what size and weight is your KZ Sportsman. Looking at the current specs, the largest fiver in that series is only a GVWR 8,800lbs trailer.

Assuming yours is of similar size, you've got plenty of tire in an ST 225/75-15 LRD. Four of those would have a rating of a bit over 10k, and an 8,800lb trailer would only ride about 6k - 7k lbs on the tires.

You are new here, and you've read all the horror stories about ST tires, but you may be missing the fact that those failures are common on big trailers where the manufacturer has spec'd tires that barely squeak over the GVWR of the trailer. Plus the fact that we've got some really noisy ST haters around here.

I suspect you're throwing a lot of money at a problem that doesn't exist. At most you could consider going up to an E rated tire in the same size, and probably only pay around $25 total extra for all four over the D rated.

On Edit: I see now where you noted the GVWR is 10k. So a little more than their current product line. Still a light trailer, and my advice doesn't change. At most you'll be running at 80% of LRD tire rating, and it would be even a lower percent on LRE tires.

[Cummins12V98]

Me Again wrote:
Or just remove the shocks and give it a try. They only have minimal value anyway.

I would totally agree if you are talking about the factory Chicom shocks! Changing to a US made quality shock does help.

[Charlie_D_]

tvman44 wrote:
BF Goodrich Commercial TA in 225x75 R16 is what I went to from 225x75 15 1" taller same width.

I did to but 2 years later one tread came off completely and another had a broken belt. BFG would not honor a warranty on either tire. Starting to see a few posts about BFG TA failures. Spending $1,000 hoping Firestone Transforce is a better tire.

[Me_Again]

Paulb1310 wrote:
Jimnlin:

Thanks for the input. I will research each of those tires. Do you have first hand experience with any of these tires?

Does anybody else have first hand experience with any of these tires in this list?

I ran XPS RIBs for 6.5 years and 40k+ miles and now R250's for two years. The R250's are about 50 bucks less per tire and just as good. Trailer is 12,200-12,400 and I run 71 pounds inflation.

I said remove the stocks and test because Cardinals had stocks for years and quit putting them on in 2011. Our club members are not running out and installing them.

I would install LT235/85R16E R250's on 6 or 6.5 zero offset wheels and deal with stocks as necessary. On trailers it is very important to have zero offset wheels centered on hub bearings. Just ask Titanium owners that got OEM axles and wheels that were not setup that way.

Chris

[padredw]

I put on four Firestone Transforce HT based on recommendation of a tire dealer who is very active on another RV forum.

[tvman44]

BF Goodrich Commercial TA in 225x75 R16 is what I went to from 225x75 15 1" taller same width.

[Paulb1310]

Jimnlin:

Thanks for the input. I will research each of those tires. Do you have first hand experience with any of these tires?

Does anybody else have first hand experience with any of these tires in this list?

[Paulb1310]

Thanks everyone for the input!!

Laknox:

Interesting comment. I did some research and discovered that the next size down in either the Michelin LTX A/T 2 or Michelin XPS Rib is an LT225/75R16. However, there is no LT235/75R16. There is a LT235/85R16 but this tire is too tall.

Gitane59:

The XPS Ribs look like a really great tire. And the reviews on Tirerack are stellar. They do appear to require a narrower wheel which would certainly help in the clearance issues. I was just trying to avoid that $300.00 cost per tire. But then, I guess some sacrifices have to be made, huh? lol

Another question:

It appears that if I were to put on the XPS Ribs that there is a range of tire pressures that I could actually run. Is it recommended to run a lower tire pressure since I will be loading the tire less than 80% of its capacity? Or does less tire pressure totally defeat the purpose of going with a larger tire?

[JIMNLIN]

Compare the 2 tread patterns side by side and you will notice a distinct difference.
The LTX AT will have very a blocky chunky tread pattern with no obvious continuous ribs of rubber running the circumference of the tire.

Excellent point for a highway trailer. Now if the OP goes off roading then that type tread will help tracking in mud/etc.
Tires for trailers need at least one solid rib in the center of the tread or both edges for best tracking/handling.

We have a much better tire tread choice with the two all steel ply commercial grade Bridgestone R250 or the XPS Ribs.

Goodyear Wrangler HT
Firestone Transforce HT
Cooper Discoverer HT3
fresh dated BFG Commercial HT
fresh dated Uniroyal Laredo HD-H