CarTalk.com Blogs Car Info Our Show Deals Mechanics Files Vehicle Donation

Wobbling like unbalanced tires, but it's not

Hello, I’m hoping someone out there might have some insight to my mysterious problem. It’s been going on for a while now so I’ve accumulated some good details to help with the diagnosis.

So, a little over a year ago I bought new tires for my 2005 Tacoma 4x4 and went up from 265’s to 275’s with some really nice Pirelli Scorpion ATR’s, problem was, I started noticing some serious wobbling in both the steering wheel and the front end in general, it seemed to be at certain speeds. I had done some research online to find that some people had trouble with the balancing on those Scorpions so I naturally thought they needed to be rebalanced. But balance after balance, nothing seemed to improve. In total I went in for balancing 6 times! Even went to different places to make sure I didn’t get a machine that was somehow calibrated wrong. I also took it in to the dealer and had them look at everything to make sure all was well with the truck, they said everything looked fine. So my frustration finally came to a head last month when after another balancing the wobble was still there, and I decided to change out the tires thinking I just got a bad set. I test drove the truck right after changing the tires and could feel a little wobble so I took it back and they re-did the balance. Sadly that was rush hour and I couldn’t get up to the speeds that I normally felt the wobble. (usually between 55-65mph) The day after switching the tires, (new tires are back to 265’s Falken Ziex all season) I took off on a nice road trip up California from San Diego to Lake Tahoe… wobble was still there. But because the trip was a nice 9 hour drive I had PLENTY of time to notice some of the intricacies of the wobbling. At first I thought the wobbling was speed dependent; BUT after setting the cruise control on the open road at 72mph I started to notice that the wobble would come and go seemingly at random. I started thinking that it may be the road surface but put that theory to rest when I felt the wobble on brand new paving (yes, believe it! California does have some freshly paved roads out there) and on older paving as well. The wobble just seems to come and go even at the same speed and on seemingly similar surfaces. It’s driving me crazy! I have to believe it’s not the tires that are causing this, but since the dealer can’t seem to reproduce the problem when they test drive I’m looking for any help that can point out the right place to look.

So to summarize; the problem seemed to start when I got new tires a year ago, rebalancing 6 times did not solve the problem, put new tires on and still getting the wobble. It doesn’t seem to be as dependent on speed or surface, although the worst of it happens in the 55-65mph range. (If I go faster it seems to smooth out, but we’re talking 75+) The wobbling is felt and seen in the steering wheel and the front end of the truck. (my gut tells me it’s coming from the front right of the vehicle). I even had them do an alignment so it’s not that either.

Please can anyone help? I look forward to your sleuthing abilities to help me figure out this conundrum.
Thanks in advance,
Didjeridug

Sounds like you may have a bent rim. The tire changing machines can bend a rim if the tire technician is not careful. It will usually occur when unmounting the old tires. The amount of deflection can be undetectable to the human eye. A dial indicator will need to be mounted with the detector running along the bead edge of the rim. Then rotate the wheel and measure the amount of deflection. Check inner and outer beads.

Thanks Keith, please excuse my ignorance but is the rim on the wheel itself or on the vehicle. I’ve had the tires rotated and the problem persists so if it feels like it’s coming from the front right side would I have them look there first? Is this something the tire shop (Evans Tires) could fix or something I need to take into the dealer?

Didjeridug–Many folks still seem to use the term “rims” in place of “wheels”.
This dates back to the days (70+ years ago) when the tire’s rim and its wheel were separate entities.
Back in those days, the wooden wheel would usually stay attached to the hub while the tire and its rim were removed for repair or replacement.

However, the correct term nowadays is “wheel”, if we are talking about the metal component to which the tires are attached. A wheel has a rim (the part of the wheel to which the tire is attached), and the rim of the wheel can indeed be bent, but when you hear someone talk about your “rims”, they are usually referring to the car’s wheels, rather than to the edge (rim) of the wheel.

The inertia of a heavy wheel/tire combination can overcome a vehicles chassis. The “death wobble” that can occur from oversized tires is very similar to the wobble caused by weak A frame bushings and radius rods. I cannot calculate the limits and won’t guess that your problem is the result of exceeding the limits of the vehicles suspension system but it sounds very familiar. Several 4x4 vehicles have been brought in with serious handling problems at highway speeds when the suspension was in perfect condition but massive tires were installed. When OE wheels and tires were installed handling was like new.

“Rim” and “wheel” are interchangable except for split truck (or heavy equipment) wheels.

Anyway, there is a technique called “roda force balancing” that balances the wheel & tire by psinning them with simulated road force applied. It presses a spinning drum against the tread while it runs. These can detect internal defects, poor concentricity, and other problems that regular balancing machines cannot. I’d be inclined to try spinning the wheels on one of these machines first. The store where you bought the tires may even have one.

Thanks for everyone’s input. I’m hoping for a little more if possible. I called the tire shop and asked about “road force balancing” as “the same mountain bike” suggested… they do have that machine available, but while discussing the problem with them… the guy said it’s pretty much impossible to bend the rim while changing the tires out. Since a few of you have stated otherwise, I’m hoping to get some more input on this possibility. This whole problem started after they changed the tires so I’m inclined to believe that yes, they did do something when swapping tires, but the more info I have, the more confident I can be in challenging the tire shop.

If you can, help yourself by jacking up one wheel at a time and then spin it with something such as a small grinding stone or a wire brush wheel in the chuck of a drill motor applied to the tire tread. A helper could run the drill motor for you. Then compare the passing tire tread with the ground or pavement underneath. This might help you to lead the experts to the source of the problem. At the least, it would tell you what is not the cause of the problem.

I know you have had the tires balanced 100 times, has any of them been on a “ROAD FORCE” balancer?? This is a special tire balancer that actually puts a roller against the tire to simulate the road. These are much better and finding bent rims, and poor tires then the older spin units. Also if you have a steering stabilizer on this truck (if you look under the front end it looks like a sideways mounted shock absorber). I would replace it with a new unit, maybe a higher performance unit. Dealing with Jeeps I have seen this cure a lot of issues.

This doesn’t sound like a tire issue. It’s a little unclear, but it sounded like the OP rotated tires from to rear and the problem stayed in the front end.

I’m thinking CV joints.

Hopefully my link will work. This OP’s problem seems significant enough that a “cure” is on the market.

http://www.automedia.com/Balance_Tires/ccr20001001rt/1

Didn’t Mercedes Benz have a similar solution 70 years ago.

The fact that the vibration comes and goes tends to point away from the possibility of a bent rim, but it is possible to accidentally bend a rim with a tire changing machine. In fact, it is quite easy. If you are in a hurry and don’t get the rim centered and level on the machine, it can catch the lip of the rim. I once did it.

The fact that your problem did not go away when you went back to original sized tires takes a lot of the wind out of my theory, but, it is the only theory I have, so I will stick to it:

My theory is that this sort of problem is usually associated with looseness in bushings or ball joints that find a harmonic frequency with the wheel/tire at highway speed. When you change the size and weight of the tires, you change the dynamics, and hence, the harmonic frequencies, of the system, such that it is seeing frequencies that the original designers never tested against. The solution to this problem can be replacing a rubber bushing with a harder compound or putting on shocks with slightly different initial dampening rate might make the problem go away, but this is very hard to predict. It might go away of you put on still larger tires. In this case, since original-sized tires are still having a problem, I would look again at all the joints and bushings. It may be that driving around vibrating exacerbated the looseness so that now it will be noticeable to the mechanic.

Failing that, I go with CapriRacer. A CV joint could let an axle move out of center at speed, though it seems that a CV joint that bad ought to make noise at some speed.

Manolito, thank for the input, I was going to say pretty much the same thing except I could not post yesterday, still having those problems with this site. I just want to add that the amount that the rim gets bent is not detectable by the human eye, you have to use a dial indicator to find it.

Regarding “bent” rims, when mounting tires a bur can be raised on a rim at a location that holds the wheel/tire out of true with the hub. But such damage should be visible to anyone who removed the rims and inspected them./Cast rims don’t really bend and warp as they would split. Traditional steel wheels can and often are bent on the old style tire changing equipment. The lower bead breaker exerted a great deal of pressure at the rims bead (edge), leveraging against the rims center that was held down by a cone.

Thank you so much for everyone’s input. I contacted Toyota Corporate and they confirmed that since I have the TRD package and Alloy wheels there is no chance of the rims being bent. They could crack, but if that were the case I’d be losing air pressure and this is not the case. So with that in mind, I have gained some further input from the tire shop after they did some tests and took it back to the dealer for the fix. Now the dealer is giving me some mixed info and I’m hoping you guys might be able to offer some info. As I mentioned above I’m not an auto expert so my terminology may be wrong, my apologies for my ignorance. The tire shop was able to show me that the two bushings in the rear of the front axle have quite a bit of play in them. They used a crow bar to push against them and showed me the two in the front don’t move at all and the two in the back do move quite a bit. They told me that this would translate into steering wheel and front end vibration at highway speeds. Seems very logical. They also said another component seemed to have a little play in it but not a lot and to start with those bushings. OK, so I took the truck over to the dealer and they’re telling me that the amount of movement is normal and they still think it’s a tire/balancing issue. This sounds like a load of crap! Can someone out there tell me if those bushings are supposed to move under the force of a person using a crow bar without much effort? I watched the tire shop do it and they showed me that the rubber is cracking slightly, so my gut is telling me this seems to be the right direction. Thanks again for your help.

I seem to recall someone above mentioning plastic suspension bushings. The oversize tires may require stiffer control of the A-frames and plastic may be needed. It’s going to be a hit and miss proposition to find the cause. Knowledgeable mechanics avoid being pinned down on tough calls like this. Can you blame them?

Hi Rod Know, I don’t have oversize tires anymore, I switched back to manufacturers recommended size… would this still cause the vibrations?

If the original suspension is in like new condition it should handle original size tires. But obviously there is a problem somewhere. You might search for someone who enjoys 4x4s and has some history of modifying them. On occasion I have found myself struggling with similar problems on old Ford Broncos and Chevy Blazers and found that suspension adjustments outside of the specifications and stiffening the system greatly improved the situation.

Since there is some disagreement on the tire issue, it’s time to find someone with a Hunter GSP9700 Road Force machine. This machine measures a property called uniformity and is independent of balance Think of uniformity as “Out of Round” and you’ll be close.

If the tires show high force values, then you can fix that by replacing the tires (or the wheels if those are the issue) But if the values are pretty good, then it sounds like the bushings may not be dampening out things.

It sounds to me like 1) you may need to change bushings as was stated above OR 2) install a steering damper which is very common in 4 wheel drive vehicles with oversize tires.

You can test usually yourself by lifting one side, grab the wheel in north/south position &wiggle back &forth…if there is play of any kind, you need ball joints. East/west play means tierods or A arm bushings. If you get NO play, then I think it is “bump steer”.

If it is the bushings, I would use neoprene & order them from a reputable manufactor i.e. Western Chassis, Readylift, Skyjacker to only mention a few.

This sounds like a common case of “bump steer” though. Check out a 4WD forum & I think you will agree.

For clarification…the metal part is the “rim”, rubber part is the “tire”, and the whole thing together is the “wheel”. But understand in my part of the country, a Coke is a soda pop no matter WHAT the flavor. ;o)