So, a couple weeks ago I changed out all 4 stock shocks for bilsteins.
While I had the tires off, I didn't do a complete rotate, just front left to front right, and vise versa. Did the same for the back too.
So, now, one my truck gets to the other side of 35mph it shakes. Eases up at 50, then around 65 it goes again.
Think this is a tire balance issue, or a shock issue? I didn't tighten the shocks much b/c of fear of bushing problems.

Any suggestions?

 

Get the tires balanced and you will be ok. Do tell them the rotation that you did so they can put those fronts on the rear.

 

You should not rotate radial tires like that. They should be rotated front to rear, keeping them on the same side. They do not like to run in the opposite direction than they have been running, and there are many tires out there that MUST rotate in only one direction.

 

I disagree. On non-directional radial tires, they should be rotated side to side, otherwise the tread will start "cupping." The whole point of radial tires is that the carcass doesn't care which way it rolls. Directional tires don't care either, except that the tread is designed to work best on one direction. If I don't rotate the tires on my 4x4 to go the other direction every 8000 miles or so, the tread cups very badly.

As far as the wobble, its not shocks. Its also possible that you simply lost a wheel weight during the swap. Its also very possible that you have a bent rim or poorly balanced tire that was masked by the worn shocks. Maybe the increased damping of the shocks is simply transferring more of the vibes to you.

The worst-case scenario is that you have a separated belt in the tire. That can be hard to diagnose, but it would present itself differently if the tire reversed rotation. The quick and dirty way to test it is to switch the tires back to their original positions. If the problem goes away, its most likely a tire issue. If it stays the same, it is most likely a balance issue that was masked by the worn shocks before the swap.

 

Reversing the direction of radials CAN cause belt shift and separation.

 

If that were the case then why do all of the tire companies void your warranty if you DON'T reverse the direction on non-directional tires?

you would think if it causes damage they would void the warranty if you DID, but they specifically tell you to rotate them side to side.

 

Since when?

I am going on many years of personal experience. Been there done that - X-rotate and the belts start breaking.

 

your tire cupping issue is do to alignment problems. I'm an Apprentice and am in tradeschool and we have actually just discussed this and tire rotations on radial tires should be performed front to rear and not side to side. cupping is probably coming from alignment issues.

 

Ok, so with my BFG A/Ts, should I switch the back to the side they were originally on, then swap front for back? Or, leave them on the side that I switched them to, and swap front and back?

 

Michelin came to town in the mid 60's with radial tires that lasted forever and you could rotate them any way you wanted.

American tire manufacturers got on the bandwagon with bias belted tires and radials. They had not learned how to make belted tires properly and that is when the directions came out not to cross the tires when rotating.

Now, if you look in the owner's manual it will tell you to x the tires when rotating.

Another little tidbit of information. The next time you look at Michelin tires take a look at the mold marks. They are radial. Most all of the others are circumferential. With steel belted tires, Michelin uses sectional molds to pull the tread rubber to the belt. The other tires uses clam shell molds that may not pull the tread tight enough to the steel belts.

I still think Michelin makes the best tires if you want round, smooth running tires. I rarely buy any other brand because when I do, I usually regret it.

My Magnum, Monte Carlo, and the wife's Mitsu has Michelins. The truck came with new Daytons. I just bought it 2 weeks ago and my son's Mustang has Kumho tires. I just bought it about 2 months ago. When the time comes, they probably will have Michelins too.

 

Hmm... I wonder who you work for.

 

I am an independent contract mechanical nuclear power design engineer. I'd love to buy Good Years since they are about the only US tire company left, but I just don't think their tires are as good as Michelins.

I have to admit I was impressed by the original Good Year Wranglers that come on my new 2000 F150 Supercab. I replaced the first two at 77,000 miles because the sidewalls were cracking 360 degrees on both sides on one front tire and 360 degrees on only one side on the other. I ran them until the one that was cracked on both sides was losing air. Then I replaced the last two at 92,000 because they were also cracking and winter was coming in Wisconsin where I was working at the time. Otherwise they would have lasted about 120,000 miles. Most of those miles were on the interstate with the cruise set.

And I did replace them with Good Year Wranglers to keep the tires matched. But, before I sold the truck at 105,000 miles the new Good Years had started cracking too.

 

JNC, I would recommend you put the tires back the way they were. If the shakes go away, then rotate them front to rear same side. If the shakes do not go away, or if they shake after rotation, take it in and have them checked for balance and out-of-round. Lug nut torque can be somewhat critical too - you should actually use a torque wrench, and tighten them progressively in a cross pattern.

I don't have to worry about stuff like this - I buy my tires at Sam's Club with the service package - free lifetime rotation and rebalance and free flat repair.

 

By the way, who do you work for? Firestone?

 

Yea, I work for firestone, but am running BFGs.