Advice On Replacement Tires

[Ford_6L_E350]

Running a spare that is 1" larger than the other tires (or 1" smaller) might be a problem if you have a Limited Slip Differential with clutch plates. It will be like constantly slipping a clutch, wear, wear, wear. A plate type LSD requires the plates to slip for the tires to go different speeds.

A mechanical locker will only see a 3% difference in speed, side to side and probably won't lock up at all. Unlocked, it is just an open differential. No problem.

An air locker is just like a mechanical locker, only under the control of the operator. No problem.

To be safe, mount it on the front axle and go with it. I don't know of anyone who has an plate type LSD on the front.

Mike

[louie]

Originally Posted by jage

I'd always thought there was nothing wrong with inflating to the max allowable, not that I do, I run 62-65 all around usually, but apart from ride quality, is there any reason NOT to inflate above the load (but not overinflate past the max pressure)?

Need to jump in on the tire pressure questions as I am a bit perplexed how full I should keep my Kumho 245/75R/16 road venture tires. There e rated, aren't worth much for going off road, but they're fairly new so will live with them until they wear out. They have a max 80 PSI rating, but the fella I bought the ride from kept them at 60 PSI all the way around.The vehicle recommendation says I should keep the back at 80PSI and the front at 45PSI. Why such a discrepancy between the front and the back...
L

[Ford_6L_E350]

This is from old thread about tire pressure:

The best method to calculate tire pressure requires weight measurements for the front and rear of the van, even better is each individual tire weight measurement. Then calculate how much pressure you should be running. This from an earlier thread:

Old school answer:

The pressure rise from cold tire to hot tire should be 4-6psi. Less than 4psi rise means the cold pressure is too high, more pressure rise means the cold pressure is too low.

Best answer:

Get the actual weights on the tires and ask the manufacturer for the proper pressure for that weight.

My method:

Again, get the actual weight. Compare it to the max weight on the tire. Do some math.


Actual weight/Max weight X Max Pressure = Desired pressure

If you have 2500# on a tire rated at 3000#@80psi you get:

2500/3000 = .8333 .8333 x 80psi 66.66psi, which I round up to 70psi


Then I always round the pressure up. Much better to err on the side of too much pressure than on the side of too little pressure.

As a general rule, D and E rated tires carry the same load at the same pressure. The big difference is E rated tires can handle more pressure, hence more load.

My van weighs in at 9800#, fairly evenly split front/rear side/side. The tires are LT275/70-18E rated at 3640# @ 80psi. For 4 tires, that would add up to 14,560# at 80 psi. My math says I have 9800/14560 of full load. That is about 67% of the max tire ratings. 67% of 80psi is about 55psi. I run 65 psi. A good safety margin. I will never run a tire at its full capacity. Just too much at stake for me.

4 tires rated at 3000# would be too close for me. Going down the road with some lean to the road, the outside tires could be overloaded for many miles. I wouldn't do it. I always want at least a 10% safety factor, 20% is better. Hence, my 65psi in my tires.

I always round up with tire pressures since higher pressures (within the max tire ratings) will reduce tire temps and might tend to wear the center of the tread. Lower tire pressures will cause higher tire temps and can easily cause a tire to fail.

Your RB probably has less weight on the rear than our EB does, hence lower tire pressure on your rear tires.

There should be enough here to confuse the issue. Good luck.

Mike

[1stiski]

TOYO Open Country HT with Tuff Duty. 285/75 R 16 , LOAD E and rides excellent on the tarmac and also is M/S rated... I've been running them for over a year now, wow, bullet proof and smooth.

[Pete]

I see a lot of comments about how well the Toyo's ride, but what about their durability? I am far more concerned about the flat protection that the ride quality. I have had some catastrophic tire failures in Baja, and don't want to take a risk. The BFG's have always come through for me.

[Roonie]

Originally Posted by Pete

I see a lot of comments about how well the Toyo's ride, but what about their durability? I am far more concerned about the flat protection that the ride quality. I have had some catastrophic tire failures in Baja, and don't want to take a risk. The BFG's have always come through for me.

There are several posts about the BFG blowouts with Sportsmobiles. Seems to be mostly D rated tires. The Toyo are 10 ply and heavy = stout as anything. I could barely get them to flex off the rim.

If you google blowout and BFG you will see a lot of comments on other 4x4 forums about the same issue.

http://www.sportsmobileforum.com/vie...php?f=2&t=3318
http://www.sportsmobileforum.com/vie...php?f=2&t=3625
http://www.sportsmobileforum.com/vie....php?f=3&t=942
http://www.sportsmobileforum.com/viewtopic.php?t=2299
http://www.sportsmobileforum.com/vie...hp?f=13&t=3334

[daveb]

I also have had good luck with the BFG's, but plan to change. The BFG's wore fast this time out. Did you see this post? Not conclusive to the weight of our vans but I'm looking at a change soon.
viewtopic.php?f=3&t=6128&start=30

[jage]

The Toyos have never delaminated or popped a belt inside on me. With BFGs I've had several failures including a sidewall cut that took out a brand new one. Naturally I have more miles on BFGs over the years, so that accounts for some of it, but both the Jeep and SMB Toyos seem like iron, just in the damage they have (or haven't) taken.

[JRO]

I've put my 2004 stock tires through Hell and today after 60,000 miles they are still doing the job. I'm guessing I've got another 15,000 miles to go. They've always looked weak, but, I'm not interested in the "show". I'll buy the exact set again.

[Pete]

Well, I exprienced a catastrophic blowout on my D rated BFG AT KO's last weekend in Baja. I'll post a pic later, but it basically disinegrated.

So, I'm realizing two things:

1. D rated tires are no good
2. Old tires are no good

So, I've gotta go with a new set of meats. I see many are singing praises of the Toyo Open Country M/T's, but what about the A/T's? Although I like the look of the M/T's, I'm not sure I really need that aggressive of a tread pattern for what I do, which is mostly dry rocky roads in Baja, 4x4 mountain trails in the Sierra, and some sand/rock/4x4 desert roads in Anza Borrego.

Not that concerned about the cash aspect, I need to get a nice set of E rated tires, and I know they are going to be expensive, any way I slice it.