Problems With 16.00 Tires

Good morning, I have been having a problem with a bad vibration on my M35A2. Its a "baby" death wobble that kicks in at about 50 mph. The truck has had it since I bought it.....I recently redesigned the steering system and made some changes to the suspension as well. I thought this may fix the problem.....but I was wrong. A few weeks ago, I had finally had enough and decided to fix the problem for good.

After some troubleshooting, I have found the problem to be the tires/and or wheels. After dropping the rear driveshaft, I raised up the front of the vehicle and locked in 4. I got it up to 4th gear and noticed a signficant shake.....I could see the tires/and or wheels were definitely out of round. I tried one of the rear tires up front and got the same out of round condition.........Although possible, I find it hard to believe that 3 tires would have belt seperation.

I already have new 2 piece wheels from Stazworks in process as well as 4 tires from miltairyoffroadtires.net on the way.

Considering this is my only experience with this 16.00 R20 XZL tires I'm hoping
there is someone on here who will tell me this is not normal, I'm trying to figure out what to expect with these new tires.

Thanks.

Have you demounted them to rim to see if they have water in them? The xzl's shouldn't need any thing to balance them other then balancing beads 20 oz max, I had a the same problem with my xzl on my truck and when I broke it down I found 5 Gal of water in it. Put the beads in and all the shake was gone.

There is no water in there. I have already seperated to look inside. The shake is too bad to be a balance issue......There is a high spot, I have placed a straight edge by the tires and spun them......I'd say its close to 1/4". Its almost as if its belt seperation.

The mfg date on the tires is 01, 02 and 04.

Did you put an dynamic balancer in the tires?. If not put in aprox 20 ounces (airsoft BBs work) ans try a drive test. These tires are so huge that 1/4 in of deflection is proportional to what a small passenger tire has. I have a feeling you bought a new set of tires and will.experiance the same issues.

Have you checked the alignment, all around? Like how is the caster, camber & toe-in? Toe in should be about 0 for radials ( the 1/4" you speak of, is nothing). The camber, you can check on a nice flat concrete floor, with a framer's square. Does the truck want to go straight down the road? Does it want to straighten back out, coming out of a corner? If it wants to wander on a straight road, it needs more castor. Loosen the U-bolts and shim the front edge of the spring pack, to increas the castor.

When all else fails, take it to a front end shop that does heavy trucks. They can sort it out - they use fat tires too, on commercial trucks.

My only alignment I am aware that I can adjust is toe in and it is good. I am on air ride so I cant shim the springs. I have played with the ride height on the right side to push the axle forward a bit and I have the same results. I can't adjust the camber.......

The steering wheel returns like normal when rounding corners.

The truck does pull to the right going down the road.

Like I said in my original post, with the front of the truck jacked up, I can still feel a good shake, plus I can see the tires wobbling out of round as they rotate. From what I can see, this is causing the shake. Everything else is tight and brand new.

I'd also like to add, everything in the hub is good it tracks just fine.

If I do decide to take it to a shop I will do so after I get the new tires.....I'm really expecting them to fix the problem but who knows......just anxious to solve this issue

Almost forgot, yes I did try to dynamic balance the tires.......However according to yall, I put way to much in. I had approx 52 oz, I didnt notice any difference. I got this from speaking with someone who had these tires on their F350 and they said it took 6 lbs. The dynabeads website said 36 oz so I figured I would start somewhere in the middle. I just tried it once........I wanted to see if I noticed ANY difference in ride. If I did I would adjust the weight, but since I didnt I just took them out.......

RHudson85 said:

My only alignment I am aware that I can adjust is toe in and it is good. I am on air ride so I cant shim the springs. I have played with the ride height on the right side to push the axle forward a bit and I have the same results. I can't adjust the camber.......

The steering wheel returns like normal when rounding corners.

The truck does pull to the right going down the road.

Like I said in my original post, with the front of the truck jacked up, I can still feel a good shake, plus I can see the tires wobbling out of round as they rotate. From what I can see, this is causing the shake. Everything else is tight and brand new.

I'd also like to add, everything in the hub is good it tracks just fine.

If I do decide to take it to a shop I will do so after I get the new tires.....I'm really expecting them to fix the problem but who knows......just anxious to solve this issue

Almost forgot, yes I did try to dynamic balance the tires.......However according to yall, I put way to much in. I had approx 52 oz, I didn't notice any difference. I got this from speaking with someone who had these tires on their F350 and they said it took 6 lbs. The dynabeads website said 36 oz so I figured I would start somewhere in the middle. I just tried it once........I wanted to see if I noticed ANY difference in ride. If I did I would adjust the weight, but since I didn't I just took them out.......

Click to expand...

OH my god there's your problem, I'm a sales rep for Counteract Balancing Beads and if you add many OZ of beads then the tires will be fighting the beads to balance out. 20 is MAX, in the case of the balancing beads less is better. Yes they will distribute threw out the hole tire but 52 oz is a lot to have in a tire, and I mean a lot. I have 6 16R20 goodyear tires on my m818 and they where not worn evenly at all and after I added 20 oz it still took about 500 to 600 miles of ware time to get the tires to the point where they where wairing evenly and it did end up smoothing out.

You might have to have the tires buffed round.

I have been there with civy truck. I would repeat test with wheels OFF. If still vibrates, then you know there are other issues - that is what I found. It was driveshaft! Then I would try with just wheels and check runout and vibration. If ok, they you know it is a tire issue, and I would follow advice in post #7.

Just an update of what I have found this weekend in case anyone is interested......

Yesterday, I pulled a tire off of the truck and seperated it from the wheel. Bolted the whell back up and found out that it was approx 1/8 radially out of round (this really isnt a surprise as C and C did such a terrible job building the rest of the truck). This makes me believe all wheels are 1/8 out as they would have all been welded on the same jig. I am unsure of how out of round the wheels are laterally as I really didnt looki into that yesterday.

Today, I mounted my GoPro (this thing is awesome by the way) to the front bumper and went for a drive. It appeared that the axle was not moving, however it did appear the shake was coming from something in the steering. However everything it brand new and checks out, therefore it leads me to believe the tires/wheels are creating excessive road force. I observed vibration in the steering arms and pitman arm.

All I am waiting on now are the new wheels from Stazworks. I am hoping these will minimize the road force a bit.

If that does not fix it, I am thinking I will have to find some of the commercial coil over steering stabilizers to combat this.

Anyone have any comments or thoughts?

Can you post the video?

The video is hd and a pretty large file.

How about post the video on You Tube or Vimeo and we can watch it there.

I drive my M817 every day for the last 5 years. During that time It has had 16.00X20 Mich. on it. They were new when I put them on. Still running the same set. I haul heavy loads and tow a 28,000 pound excavator and 24,000 pound dozer around a couple times a week. You very well may be on the right track, but there are a lot of variables that are different on your truck. Air bags, custom axle location systems, and different suspension and steering geometry to name a few. I would like to know your rolling empty and loaded weight of your rig, but I can tell you from my own experience with my truck, which is a different critter than yours, that the only time I have had any vibration issues is when my tire pressures were not balanced. My empty weight is 24,000 and my GVW is 48,000 and I run around at 48,000 about half the time. In the first year I ran these tires, I played around with different tire pressures to make sure I had stability (minimum sidewall flex) when loaded and that my tires would wear evenly. My tires are rated at almost 15,000 pounds each at 110 psi at 55 mph. I have run mine at 60 psi for the last four+ years and they are performing and wearing perfect. The only time I get a shake is when one or more drops pressure. I would assume that you have made sure that the pressures are equal, but you should measure the circumference of each tire fully inflated.

Do you have lock outs on the hubs? If not you may have a bad U-joint. Or possibly a bind in the differential, I am in no way knowledgeable about these diffs.

Rick

I have played with the tire pressure. Originally it was at 100 psi for 3 tires and 80 psi for 1 tire. Extremely brilliant when the dash plate says 50 psi. My truck weighs 12500. I am down to 45 psi and pretty happy with that.......I noticed a bit smoother ride.

At this point I am just going to wait for the new wheels to show up. I called stazworks today to ask about their tolerances. They told me DOT is about .040 for the wheels......righ now I'm between .100 -.120. They also said the wheels I get will be .020 or less as they put the wheel on their lathe to ensure it tracks straight.

I have lockouts on my axle and they are on 4x2.

If I still have prob with the new wheels/tires I will attempt to balance them. Its kinda hard to balance something that out of round.

Just wanted to give everyone an update in case someone runs into something similar in the future. I got my new wheels from stazworks and got everything mounted up this week. What a difference. The problem ended up being the wheels made by C&C EQUIPMENT. I am extremely disappointed at the quality and craftsmanship of his work. Take some pride in what you do....if your going to make something do it the right way even if it takes a little extra time......