BFG K02 rotated and cupping

[Grug556]

Guys I was wondering about how often you rotate your K02s? I have a new set and rotated mine the first time at around 3800-4000miles last night. Prior to that I noticed abit of squirm and instability on straight line at times. Any how I noted upon removal that the inside blocks on the tire are showing minor signs of cupping even at this low mileage (about 1mm drop on edge of block). Outer blocks appear fine, just the inner smaller double block, where one side of the block is wearing (cupping) and the other side has little to no wear. I have heard cupping is common in these tires. Anybody have a sure fire rotation interval to keep them ground flat? BTW mine were 265/70/17s C's loaded to 42psi on 8.5 inch rims. Model is a 16 Limited.

Anybody have any tricks to keeping them even? Thanks

 

[Bluestone13]

??

I don't have an answer, but very curious. I just put this same tire on my ride...

 

[Jetboy]

I would start with an alignment. Typically inside tire wear is from having toe set to zero or negative.

 

[TEujunga]

I would start with an alignment. Typically inside tire wear is from having toe set to zero or negative.

OK, I'll bite -- how could having zero toe possibly increase tire wear?

 

[Grug556]

I would start with an alignment. Typically inside tire wear is from having toe set to zero or negative.

I was wondering if the toe was slightly out might explain the high speed minor tracking issues. Not tramlining, more slightly wandering around the lane.

 

[Tisoy281]

Why are you running 42 psi?

 

[Grug556]

Why are you running 42 psi?

The tire at 38psi has to much treadsquirm and sidewall movement. 42 is much more stable in cross winds etc. IT can take 50 as max pressure. 42 for a C rated is not that high.

 

[randomguy]

Running too much air in a tire can cause cupping. Have you done the chalk test?

I ran 34 PSI on my Tacoma, still experimenting with my 4Runner. I had Bilsteins and Eibachs on the Tacom and the ride was perfect. 4Runner is a little squishy but that's the stock suspension for you.

 

[jrandom]

The truck is a little heavy for a LT C-rated tire. The C-rated BFG KO2 is LT 112/109 just under the OEM Dueler Tire which is rated at P 113. I might be wrong but a layman looking at numbers, if you have extra weight on the truck you min should be a D-rated, right?

I run on road trips at 40psi and around town 38psi (BFG KO 1's). It drives better at highway w/ 40 for me anyway.

 

[Grug556]

Running too much air in a tire can cause cupping. Have you done the chalk test?

I ran 34 PSI on my Tacoma, still experimenting with my 4Runner. I had Bilsteins and Eibachs on the Tacom and the ride was perfect. 4Runner is a little squishy but that's the stock suspension for you.

Ill try the chalk test. THought it was odd that cupping was only appearing on insides on second blocks. No sign of any wear otherwise. Ive had Michellin snows on prior to this for about the same mileage. Zero cupping or other signs of wear. Could be the K02 block design maybe. I have noticed after rotation though that they are back to being very quiet again (not that noisy before, but now silent) and also have regained some of their straight line composure.

Odd ive had cupping issues on high end sports cars before, but not like this.

 

[Ron4RNevada]

48000 miles on my Toyo Open Country (E) rated M/Ts = NO cupping at all. Aligned to recommended toe in and usually at 40psig at all times.

Way way way back when I used to run BFG TA/KOs they wore much faster than the Toyos do - I expect that might be due to the older BFGs had softer rubber compounds.

 

[83Mule]

Toe out......shocks shot? I go 5 to 7.5K for rotation.

 

[gerfunken]

I think there's a couple of different things in effect here.

Typically, the front tires will spread out a bit in the front (go toe-out) under acceleration, which is why most alignment shops will set the to at 1/16" to 1/8" toe-in.

If they are set at zero, then while driving, your toe-out would increase, leaving the inner edge vulnerable to scuffing, wearing out prematurely.

Camber is another aspect as if you have to much, the tires are resting on the inside edge of the tire, which will wear faster than the outside edge.

Cupping can be an issue with a tire being out of balance and/or shocks that are starting to go, causing a small, repetitive bounce in the tire causing the cupping.

As someone said earlier, start with an alignment, and have your tire shop rebalance them. Or, better yet, find a place that does the balancing on the car, so you can also account for all of the rotating parts.

 

[Jetboy]

OK, I'll bite -- how could having zero toe possibly increase tire wear?

On a level and flat road going straight with perfectly balanced tires, zero toe would probably be ideal.

On crowned roads with corners zero toe will result in amplifying every suspension joint's small amount of play or backlash because it's unstable and rather than having a stability from loading all the joints in one direction on each side, it would cause the system of joints that locate the wheel to wander on almost any imperfection. Assuming the front is not a driven axle most of the time. It would also cause drag on the inside tire in cornering because the slip angle would be greater if the ackerman angles are designed for toe in. So it may have more wear in normal driving due to the slip angle on cornering.

I suspect one major issue that the front suspension has in the 5th gen is that some models are awd and some are rwd. For a driven front axle you typically want tow out. For a rwd you want to in. How do you design a system that does both? You don't. You have one that does nether as well as it should. And the result is what I think is the primary cause of so many people having front end shimmy issues. The toe is set near zero. And that's not a great design IMO. The awd should have different alignment than the other models, and different spindles with different steering arms, and probably even different control arm mounts.

 

[03_4x4Runner]

Ill try the chalk test. THought it was odd that cupping was only appearing on insides on second blocks. No sign of any wear otherwise. Ive had Michellin snows on prior to this for about the same mileage. Zero cupping or other signs of wear. Could be the K02 block design maybe. I have noticed after rotation though that they are back to being very quiet again (not that noisy before, but now silent) and also have regained some of their straight line composure.

Odd ive had cupping issues on high end sports cars before, but not like this.

I thought the chalk test could only be done on a relatively new tire. You already wore the tread out to make it flat now.

 

[TEujunga]

On a level and flat road going straight with perfectly balanced tires, zero toe would probably be ideal.

On crowned roads with corners zero toe will result in amplifying every suspension joint's small amount of play or backlash because it's unstable and rather than having a stability from loading all the joints in one direction on each side, it would cause the system of joints that locate the wheel to wander on almost any imperfection. Assuming the front is not a driven axle most of the time. It would also cause drag on the inside tire in cornering because the slip angle would be greater if the ackerman angles are designed for toe in. So it may have more wear in normal driving due to the slip angle on cornering.

I suspect one major issue that the front suspension has in the 5th gen is that some models are awd and some are rwd. For a driven front axle you typically want tow out. For a rwd you want to in. How do you design a system that does both? You don't. You have one that does nether as well as it should. And the result is what I think is the primary cause of so many people having front end shimmy issues. The toe is set near zero. And that's not a great design IMO. The awd should have different alignment than the other models, and different spindles with different steering arms, and probably even different control arm mounts.

Good explanation, makes sense. I understood why zero toe is bad for stability. I guess if that instability results in a lot of steering corrections from the driver and steering components being alternately loaded in opposite directions, tire wear could indeed suffer.

Probably accounts for why different T4R trims have slightly different toe specs: IIRC, the SR5 specs call for slight toe-in while the Trail is slightly toed out. Perhaps Toyota is acknowledging that Trail buyers will spend more time in 4WD? It's all a compromise, in any case.