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BFG All-Terrains and Tramlining


rpn453
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I had a set of Goodyear Forteras (265/75R15) on my Pathfinder when I bought it in the spring. It drove fine, but they were highway-only tires and I planned on upgrading them with new 31X10.5X15 BFG ATs along with new rims in the spring. Due to a flat, I ended up getting two ATs early and putting them on the back. With the ATs, my back end was getting thrown all over the place by grooves in the road. Now that I have four Cooper Discoverer winter tires on there, it drives fine again.

 

It's not ideal to have different pairs of tires on a vehicle, but I've never experienced anything like this with any other vehicle. I've tried different tire pressures, I have new shocks and struts, my wheels are aligned, my front-end components are good, and all the suspension bushings look good.

 

Does anyone have BFG ATs on their Pathfinder? What do you think of them? Any tramlining?

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I've never had any kind of serious tramlining from any truck tires. My 31" BFG AT's didn't have that problem, and neither do my 32's.

 

On the other hand, my 2 other cars, which have low-profile performance tires, tramline like heck all over the place. At times it feels like I'm in an airplane, being buffeted from side to side by air turbulence.

 

It's possible that because your tires on the front are different from the rear that there is a more pronounced effect. Or, perhaps the square shoulder of the BFG AT's is the cause...

 

I would recommend switching the AT's to the front wheels and seeing if that helps.

 

Also, have you ever had the rear lower control arm bushings replaced? Swaying from side to side is a common symptom of bad bushings.

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Ive heard a lot of positive things about the BFG AT's... theyre a good tire!

Ive heard a lot of positive things about the BFG AT's... theyre a good tire!

 

 

I heard a little differently... I heard they turn into slicks with any mud or snow?

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I heard a little differently... I heard they turn into slicks with any mud or snow?

Considering that the BFG AT is not a mud-terrain tire, it follows that its performance in mud wouldn't be so great. (Just about every review I've read concurs.) It's important to understand the limitations and benefits of the particular tires you install. If mud is your fancy, an AT tire is not going to meet your needs. As for snow, its consistency and depth will be big factors on how well the AT performs compared to another more agressive tire. In shallow, hard-packed snow, they're better. In deep, wet snow, they may load up.

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In shallow, hard-packed snow, they're better. In deep, wet snow, they may load up.

 

 

Hmm. DO you think an A/t tire is better for hard snow and M/T for slush deep stuff?

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At least with my experience with Car Tires tramlining seems to be related to sidewall stiffness. I have had some that Tramline like a mother (Sumitomo and Pirellis) and some that don't (Falken and Continental) all being 225/40/18's.

 

I by no means am an expert but that is my observation.

 

Kevin

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Hmm. DO you think an A/t tire is better for hard snow and M/T for slush deep stuff?

Deep, wet snow behaves a lot like mud. The lugs on M/T tires act like "paddles" to help provide traction.

 

On hard-packed snow, the siping on A/T tires provide lots of biting edges to "grip" the hard, icy snow.

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Is it tramlining or "sashaying"?

 

I agree that some low pro's are much more prone to tramlining.

Mixing tires front and rear caused a dramatic "sashay" on our BMW. We have 225/45-17 sport (very stiff and short sidewall) tires for summer, and 205/60-15 Winterfire (tallish and very soft sidewall) for winter. Keep in mind these end up being almost exactly the same diameters.

 

While I was away on a business trip during the summer, my wife had a rear tire that was cut. A neighbor came over to help her, and he did conclude that mixing a 17" and a 15" on the rear would be a bad idea, so he changed both rears to the winter tires, but left the 17's up front.

 

OHMYFREAKINGAWD - the car was literally IMPOSSIBLE to keep in a lane - it was like the rear control arms came loose and the rear tires were randomly turning from side to side. Swapping the fronts to the 15" winters as well brought everything back under control.

 

So my conclusion is that mixing stiff and soft sidewall tires front to rear is a bad idea. Having all 4 stiff or all 4 soft doesn't make much difference, but mixing is bad.

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I think this was the combo's and results:

 

Forteras all around: OK

Forteras in front, Goodrich in rear: Yuck

Coopers all around: OK

 

I'm thinking the sidewall stiffness of the Goodriches being way different from the Forteras is the root cause. I would wager all 4 Goodriches will be fine.

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I'm thinking the sidewall stiffness of the Goodriches being way different from the Forteras is the root cause.  I would wager all 4 Goodriches will be fine.

I think it's that, and, as XPLORx4 mentioned, the difference in shoulders. The ATs have a sharp transition, while the Forteras were very rounded. Four BFG ATs would probably be okay. I'll consider this my lesson in tire mis-matching.

 

OHMYFREAKINGAWD - the car was literally IMPOSSIBLE to keep in a lane - it was like the rear control arms came loose and the rear tires were randomly turning from side to side. Swapping the fronts to the 15" winters as well brought everything back under control.

 

Sounds exactly like what I had. I guess you could call it "sashaying": tramlining with the back end only.

 

The BFG ATs have the severe winter service snowflake rating, so they must be pretty good on hard-packed snow. Like most of you, I'd think that MTs would be better in slushy or really soft sticky snow and maybe even really deep stuff too.

 

The 205/50R17s on my Mazda3 don't tramline at all. I could do a 300 mile trip on grooved roads with just a finger on the steering wheel. I've had Goodyear RS-As (stock) and Michelin Pilot A/S (current) on there.

Edited by rpn453
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  • 4 months later...

This "tramlining" or "sashaying" you guys speak of - I think I am experiencing this now for some reason.

 

Does it feel like the truck has gotten "loose" in the rear and wants to slip from side to side? I've been trying

to figure this out for weeks now.

 

I seem to experience it more when the road is wet but it has nothing to do with a windy day or following a

tractor trailer or anything that would be air-buffeting related. And I do not feel this motion in the steering.

 

My tires are pretty well worn - BFG ATs with less than 5 to 6/16 of an inch left. The tire pressures match, but

I will now be looking into the lower control arm bushings. Anyone know a quick and easy way to check the

status of the bushings?

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Thanks for the link, xplorx4. I tried the test and did not notice any movement in the control arms, at least not laterally. The one thing I did do was to grab the control arms and was able to move them - I could twist them forward and backward (as you face the side of the vehicle) and they moved rather easily, more than 1/8 an inch each way. I'd say the bushings are shot.

 

I've had well-worn BFG's on my pathy before and never experienced this tramlining issue, so I'm not thinking it's the tires.

 

I'm going to order two bushing kits from AC and have access to a hydraulic press. Anything else I need to know before I get involved with this repair, i.e. what bolt size is needed for the ones I might have to hack off?

Edited by dkpath96
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