[humyum]

Hey guys i got mrf ZVTS 145/80/r12 fixed in my 800 around 900 km back with 2 new rims for the front tyres
Got it balanced at gaurdex tyres and aligned too..The car was running perfectly for about 800 km after which a trip to panvel day before yesterday saw the steering vibrating a little at speeds above 80.
Though some weight might have fallen off.
Go to a balancing fellow and ask him to balance both the front wheels.The balancing is done and there is a highway nearby.Run the car and to my horror now the vibration has increase a lot and anythin above 70 sees the steering vibrate
Sense that maybe the balancing fellows machine is gone and go to another guy and ask him to balance the front wheels
While balancing the front wheel one tyre was rotating perfectly on the balancing machine while the other was not rotating in a perfectly roundish way.The mechanic said that tyre jum maara hai.
he balanced both the front wheeels and out i went to try the car on the highway again with the balancing fellow accompaning me.
Touched 120 but no vibration what so ever.
Wht i din understand was ..what did he mean by tyre jump maar raha hai?although even i saw that one tyre was not rotating in a perfectly roundish way on balancing machine.The rims are all new with no bends
He said maybe the tyre is defective.If the tyre was not rotating in a total roundish way on the machine it would be rotating the same way on thecar too.And if this way the case there would be vibrations present on the steering wheel right?But the steering wheel is perfect now with no vibrations of any sorts?what do u guys think i should do?

[viper]

Hi,

From what you describe it looks like the rim is not perfect. Your tyre may be rotating "out". Check the wheel rim if it is a proper circle.

Viper

[humyum]

The rim is brand new...900 km old with no bends.Asked him to check the rim too.he said rim is pefect.But i dont get the thing that if anythin is wrong with the tyre.How come no vibration what so ever?

[nitrous]

PROPER wheel Alignment is also a factor for high speed vibrations.

[esteem_lover]

humyum, how did the tyre guy fix the problem ? did he only balance it again or did he align it too ?

[tsk1979]

The tyre could be a problem. This happens when the steel belt inside the tyre is bent.
Try this. Find a very very smooth road. Drive at 10kmph, see if your car rocks sideways, if it does it either means heavily bent rims or the bent steel belt.
One of my earlier MRF ZVTS had this problem. The tyre guy told me to make it a spare. Car ran fine after that.

[humyum]

Nitrous wheel alignment is ek dum perfect.No pullin to any sides and perfectly goin straight.
Now me getting 2nd thoughts that what i have mentioned is a problem or no?as nothin vibrating and nothin happenein in the car which is unusal.but just the tyre balancing ki place pe the tyre was rotating not in a perfect round thing on brand new rims
No one is answerin my original question.That what is tyre jump maar raha hai?if it is jumping as the guy says..why not any vibrations?

[DueLLeR]

I have the very same problem and I continue to live with it. See my thread about the problem: http://www.team-bhp.com/forum/tyre-a...F+ZVTS+problem

The guys at the tyre shop cannot "perfectly" balance the tyres. They say MRF ZVTS is a bad radial and such problems do eventually crop up.

If you have managed to fix your problem, please tell me what exactly the mechanic did to fix it. I'd love to try that too before I chuck these tyres for new ones.


Cheers!
DueLLeR

[rahul_intlad]

Forgive me for being stupid but is 145/80/r12 the right upsize for a maruti 800,since I did not find it in any of the tyre manufacturers recomendations.

[kpzen]

To me its a defective tyre case....

KP

@ Rahul: Seen many M800 with 145/80-12 tyres with no prob...
Isn't the stock size 145/70-12???

[Ram]

Tire "jump maar raha hai" is what's called Wheel-tramp.
The wheel tends to move up-and-down in a bouncing motion due to static imbalance or an out-of-round tire or wheel.

Wheel defects
Some amount of deviation from round can be corrected by weights.
But when the magnitude of weights gets high, you have cause for concern!

Alloy wheels being cast and machined (the expensive ones being forged), they tend to be more true and round, than pressed and welded steel wheels.

Tire defects
Then as tsk1979 says, the steel-belt in the tire carcass could have been defective. In this case, you would have noticed the high weights necessary to balance the wheel-tire combo. But certainly they would have shown their "Aukaat" while new itself.

Another thing about Radials
Radials should never be switched from left to right, ever in the life of the tire.
Ensure that tires used on the left hand side of the car are never used on the right.
And vice-versa make sure that tires used on the right hand side of the car are never used on the left.

Why?
Because switching sides (right to left) will cause the tire to rotate in the opposite direction. Radial tires do not like this! Once a radial tire is turning in one direction you don't want to upset it. Imagine that they get cranky!

The steel-belt in the radial will "set" in the direction of rotation. If you reverse the direction by switching it to the opposite side, it would cause the steel belt to cut its way loose as it tries to set in the other direction.

Also, switching rotation direction will cause a radial tire to "scallop" and get "out of round".

Switching sides was only fine when all our Ambassadors and Fiat-1100s and Heralds ran bias-ply (non-radial) tires.

So what happens to the spare?
The virgin spare tire becomes left-handed or right-handed depending on first use. After the first rotation, ensure you remember whether the spare is left handed or right handed.

Ram

[epyupc]

Originally Posted by ram

Because switching sides (right to left) will cause the tire to rotate in the opposite direction. Radial tires do not like this! Once a radial tire is turning in one direction you don't want to upset it. Imagine that they get cranky!

The steel-belt in the radial will "set" in the direction of rotation. If you reverse the direction by switching it to the opposite side, it would cause the steel belt to cut its way loose as it tries to set in the other direction.

Nice info...however just a doubt.

I'm guessing that any tyre has to withstand forces in two directions...

On the drivers side (in India) ...

When accelerating, the force lines will be a clockwise spiral ( i hope you understand my crude way of explaining it...)

When braking, the force lines will be anti-clockwise

SO, aren't the tyres anyways used to having things reversed often?
(ofcourse the force of braking is usually much more than accelerating)

[humyum]

Guys new developments.After just postin this thread and recieving few replies off i went to mrf showroom(gaurdex tyres).Told him to check the tyres right then and there.He checked the tyres for roundness on the balancing machine and rotated it.His balancing machine was an imported and a jazzy one.He checked and said that balancing thoda out hai even thought i had just balanced it yesterday at another tyre fellow and the car was running perfectly fine even at 120 and even at 80.The main reason i went to the mrf guys was because the other tyre fellow had told me about the jump maar raha hai thingy.
Ask him to add whatever weights is necessary.He does the needful and the front two tyres seemed balanced properly again accordin to him.
Now is where the sad part starts.Hit the highway and as soon as the car reaches 70 km the steering starts vibrating.*** and at 80 it is vibrating even more.Go back to the mrf show room after doin some high speed runs and making sure its vibrating because of inbalance and not because of the roads.
He again removes the tyres and says 5 grams ka farak aa raha hai and balances it again.
Fixes back the tyre and again we go on a test drive with him present with us.The car goes uptil 80 with any vibration and there is little traffic so i decide to turn back as the problem seems solved
While gettin back home get a clean piece of road and push it till 90 and again the vibrations start.JAM the brakes and stop at the side of the road.
Dont know what to do now until a bright idea strikes my mind.Why not go to the same balancing fellow whom i had been yesterday and he had balanced my front 2 wheels.
Go to him tell him the entire issues.He says he will check the balancing again and wola..the left side wheel needs more 15 gms of weight and the right side is ok.He adds the weights and go on the highway for a high speed run.Touch 120 and no vibrations at any speed.Thank him to the extent of giving him a jaadu ki jaapi..My problem is solved but he still maintains tyre jump maar raha hai and the steel belt is the problem.Where as the mrf guy when had put the tyre on his balancing machine the jumpin thing was hardly noticible
Moral of the story-the vibration problem is all gone about the jumping thing i dont know whom to trust
The mrf guy with his jazzy balancing machine could not balance the tyres properly where as the road side balancing fellow with his indian made simple balancing machine could figure out the inbalance accurately and solve my problem

[tsk1979]

Good that your problem is resolved. Same problem was there with my ZVTS tyre and Vijay wheel alignment fellow diagnosed it as "Belt bent problem". He said he will put heavier weights and there wont be a problem. The tyres did around 37K of service after which I decided to go tubless.
During this tenure I drove at speeds upto 160kmph too, and there was no problem of vibrations etc., so I guess you can stick to this person as your wheel balancing dude. I used to drive all the way across the city to Vijay wheel alignment, because I trusted that shop!

[DueLLeR]

lol!

Please tell me where your road side puncture wala can be found. I think I will go to him for all my future tyre-related needs!