Front Tyre outer edge wear - any remedy? 2

[senjim]

Hi all
I'm having a minibus with FAW of 3Tons (with 7.5 X 16 bias ply tyres). Its having a serious wear in front tyres outer edge (tyre outer Corners wears making feather like appearance). People say that its due to taking turns at High speeds & this issue is unavoidable & harmless. What do we call this type of tyre wear & what could be the reason? is there any way to rectify it?

Cheers
sen

 

[carnage1]

if it is being caused by high speed cornering you need a bit of negative camber added to your suspension setup. it also could be caused by incorrect toe adjystments. have you had the car alligned recently?

 

[senjim]

thanx. well the vehicle is not a car, it's a minibus with a camber of 1.5 deg & 0mm toe setting

sen

 

[carnage1]

the feathering makes it sound more like a toe issue than a camber issue. usually camber wears the outer edge smoothish. I would check to make sure your tie rods aren't worn and try 2mm of toe.

increasing negitive camber or toe out will reduce wear on the outer edges of the tire. If you have acess to a tire pyrometer you can do alignmnet changes and estimate the wear patterns all the same day. the hotter areas wear faster.

 

[GregLocock]

Yes it does sound more like toe.


I assume that camber is negative? ie top of the tyre is in at the top? 1.5 degrees is a lot either way.






Cheers

Greg Locock

 

[senjim]

The 1.5 deg camber is positive. tires are out at top.
can i get some more details about tire pyrometer? wat is it meant for actually?

sen

 

[GregLocock]

Positive camber would be expected to wear the outer shoulder.

A pyrometer measures the temperature, typically race teams measure the tread temp across the tread, to determine their camber and toe settings.





Cheers

Greg Locock

 

[NormPeterson]

A combination of positive camber, underinflated tires, and moderately hard cornering?

It's not clear whether compliance in the front end will result in a slight amount of toe-out or toe-in under driving conditions. Nor whether it's front wheel drive.

It also crosses my mind that 7.50-16 might be a little on the smallish side for 6000 lbs.

Norm

 

[evelrod]

I agree, +1.5 is an awful lot and would definately cause excessive outer shoulder wear but---
I still think the "feather" would more likely be the result of a toe condition --- reverse ackerman? Negative caster? Just guesses on my part. Any good front end shop should be able to rectify your problems.
7.50-16 8 or 10 ply bias were used on most medium trucks in the U.S. as I recall. I had them on my 77 Dodge with a 9500gvw.

Rod

 

[senjim]

well the vehicle is having a rigid front axle beam & stub axle where i cannot change the camber setting unless i order for new stub axle specially machined to give lesser camber. Its a rear wheel drive vehicle with a rear wheel track slightly less than front wheel track. Some literatures say that in this case its preferred to have a slight toe-out to avoid feather wear on outer edges. Any comments?

sen

 

[carnage1]

give it a bit of toe out and see. it should help

 

[evelrod]

Yes, senjim. One more comment---just bend the axel beam until some or all of the positive camber is neutralized. With I-beam front axels camber has always been "adjusted" this way. I would shoot for a bit negative camber but at least "0".
Also, since it's a beam axel, check for proper king pin inclination.

Bottom line---You need to visit a reputable front end shop that services TRUCKS! Your problem is not normal and may be the result of damage to the front suspension.

Rod

 

[senjim]

Thanx all.... i'l try out the toe-out first as this is simple to adjust..& then alter the camber..

Cheerz
sen