14.5 xl rear tire harmonics

[ncduece]

i put 14.5 xls on my truck single on the rear with the outer dual mount. at certain speeds i get a bad harmonic shake. at 55mph about ever 30 secs. i have removed the inter axle shaft to try find the problem. do i need to flip the hubs so the tire mass will be in closer to the axle? could the weight of the tire being mount ed a single outer dual configuration be the problem? at first i thought tire out of balance/round. i have a spare tire and have done some swapping and still have the problem. i have the xls on stock rims with tubes so getting them balanced seem to be a issue at the tires shops. has anyone done the hub flip and solved this problem? thanks

 

[rchalmers3]

at certain speeds i get a bad harmonic shake. at 55mph about ever 30 secs.

Hey,

That sounds like a drive shaft harmonic, not tires. Might explain why swapping tires has no effect.

BTW, have you double checked pressures? Yeah, thought you did!

BTW(2), the front axle is dis-engaged, right? Of course it is!

Others may chime in, but I'd recommend dropping the shafts and feel the joints for looseness and/or stiffness.

Rick

 

[BFR]

have you tried playing with different amounts of air pressure?

 

[tm america]

check your wheel bearing mine did the same thing when i swicthed to 14.5s two days later the right front bearing let go totally almost lost the wheel when i was going about 70 by the time i got it stopped it cut al the way through the spindle into the axle shaft . its the axtra weight that shows you what was already bad

 

[BFR]

beat me to it... anyone know what the m35a3 airpressure spec is?

 

[ncduece]

my thought was the extra weight of these tires set outside of the axles and not having the inner dual to counteract it could be the problem, the ujoints feel fine there is only slight play in the splines, and they are aired up to 70psi

 

[tm america]

i flipped my hubs but dont think it will matter as long as bearings are good but flipping the hubs is the right way to do it it makes the rear track the same as the front and puts the load where it should be plus you can chech your bearings when you are flipping the hubs killing two birds with one stone

 

[ncduece]

my thought was the extra weight of these tires set outside of the axles and not having the inner dual to counteract it could be the problem, the ujoints feel fine there is only slight play in the splines, and they are aired up to 70psi

 

[gringeltaube]

...............................and they are aired up to 70psi

70psi is a lot!! Try 45 F/TP, 35 R/TP unloaded; 50 all around at max. load.
Doesn't need more!

But your real problem is tire/wheel/drum balancing, 100% sure!

G.

 

[ncduece]

whats the best way to balance these tires being that they are on the stock rims with tubes?

 

[FMJ]

Has anyone tried these?, I'm looking at them to use on my truck with 12.5 20 XL's

Tire Balancing Products

 

[ncduece]

can you use the beads with tubes?

 

[FMJ]

Yes, I didn't see anything there saying no. . . and they mention classic cars with tube tires.

 

[ncduece]

im thinking of trying a quart of anti freeze in each tire has anyone tried this?

 

[Bob H]

So am I the only one that thinks maybe a 14.5" wide tire is too dang wide for the stock rim????????????

 

[gringeltaube]

No, you are NOT!

But even if he had them mounted tubeless on the correct size wheels (20x11 MPT) doesn't solve his problem. All tires need balancing if run at highway speeds.

G.

 

[gringeltaube]

whats the best way to balance these tires being that they are on the stock rims with tubes?

The "best way" IMHO is what I've been doing for years with ALL my tires/wheels no matter what size, vehicle application, tube type or TL...

Start with a good spare hub, install it on a spindle via adapting a pair of ball bearings lubed with light oil only, mount on an adequate (horizontal) support shaft. Check for zero runout of the mounting flange and balance the hub itself. If done right it should start spinning with as little as a 1/4-oz weight applied to one stud (pic #7). That's how sensitive and precise this home-made device actually is!

Mount your wheel/tire combo; determine the "light spot"; clean the area (on the wheel inner side) and start selecting lead weights (from your own collection...), and use duct tape to hold in place, temporarily.
After confirming that everything remained in perfect balance, the weight gets glued in place with industrial PU adhesive/sealant (Sikaflex 221 or equivalent). Eventually paint over for better looks.

This is called statically balancing. Not perfect but 95% effective, for sure!

G.

 

[ihscoutsniper]

Gringletaube, what is PU adhesive? I like your idea and will give it a try..

 

[gringeltaube]

Poly-urethane adhesive (search for Sikaflex 221 or equivalents).
X-many uses like car/ truck body repair as well as marine applications, sea containers and therelike.

G.

 

[tennmogger]

I have tried balancing beads in 14.5 Michelin XL's on 20 x 11 rims. Beads didn't solve the bounce/balance problem. Took the tires to a truck tire store and had them spin/dynamically balanced with weights. No further problems. None of the tires needed over 8 ounces to balance, one needed none. Yet up to 22 ounces of beads did not fix the bounce. Neither I nor the bead distributor can adequately explain it.

About pressure in an XL: After going through 2 sets of surplus XL's, now beginning the 3rd (mileage total about 70k km), and trying to find pressure that gives least wear and most even wear, lower pressure is the key. With Michelins the sidewalls are the magic. Let them flex, and there has to be noticable bulge to allow that. If the sidewalls flex, the tread blocks don't squirm. I run 32 psi and that's with 3500 lbs load on each tire (tires rated at 7100 lbs at 70 psi, I think). [edit: does not apply to old dried out tires!!!!]

At higher speeds, check for tire heating occasionally. I can always hold my hand on the tire sidewalls.

Bob (U-1300 Unimog)