Uneven tyre wear

[Stewart Hargrave]

I had new tyres fitted a few years ago to my '87 740, and at the same
time had the tracking (toe-in) set. The front tyres wore down on the
outside edges far more than the rest of the tread, so I had the
tracking rechecked at a different place.

In the past year I have replace all the front suspension bushes and
steering joints, including the bottom ball joints, track rods (tie
rods to you US citizens) with the inner ball joint, and the outer,
track rod end joints. I then had the tracking reset. Then I swapped
the front tyres with the rear ones, which wear evenly.

But after six months use, the outer edge - the first inch or so round
the circumference - has again worn right down to near baldness on both
fronts.

Steering seems fine (though I've often thought this 740 steers like a
whale compared to a 240) with no play, and no pull to one side, and no
tendency to wander.

The only thing left that I can think may cause this is that the camber
is out of adjustment, but I think this can only be altered by
replacing the stock suspension arms with ones of different lengths.

Anyone think of anything else that may cause this, before I try and
find someone with a rig that can check the camber?
--

Stewart Hargrave


For email, replace 'SpamOnlyToHere' with my name

 

[Mike F]

I had new tyres fitted a few years ago to my '87 740, and at the same
time had the tracking (toe-in) set. The front tyres wore down on the
outside edges far more than the rest of the tread, so I had the
tracking rechecked at a different place.

In the past year I have replace all the front suspension bushes and
steering joints, including the bottom ball joints, track rods (tie
rods to you US citizens) with the inner ball joint, and the outer,
track rod end joints. I then had the tracking reset. Then I swapped
the front tyres with the rear ones, which wear evenly.

But after six months use, the outer edge - the first inch or so round
the circumference - has again worn right down to near baldness on both
fronts.

Steering seems fine (though I've often thought this 740 steers like a
whale compared to a 240) with no play, and no pull to one side, and no
tendency to wander.

The only thing left that I can think may cause this is that the camber
is out of adjustment, but I think this can only be altered by
replacing the stock suspension arms with ones of different lengths.

Anyone think of anything else that may cause this, before I try and
find someone with a rig that can check the camber?
--

Stewart Hargrave

For email, replace 'SpamOnlyToHere' with my name

As just said in another thread, different tires are different. Maybe
these tires need a little more air. Assuming your "tracking" (we call
it "toe" over here) is set correctly, and you're not driving around
corners very fast all the time, and nothing in the suspension is bent or
worn out then camber is all that's left.

Camber can be adjusted by repositioning one of the studs in the top
strut mount, the ones that pop up through the strut tower. Camber can
be checked fairly easily with a plumb bob and tape measure, assuming
your wheels are straight. Roll to a stop (no brakes) in the most level
parking area you can find. Hang a plumb bob from the fender (wing to
you), and measure the difference in distance from the top of the wheel
to the bottom. This will let you know if you're in the ball park. On
degree is 6.2mm on a 14" wheel, 6.7 mm on a 15" wheel. Assuming that
you can find a level spot and are patient, you can be amazingly
accurate. (It's a good idea to repeat your measurements while pointed
in the other direction in the same spot to see if they are repeatable.)
Note that any adjustments to camber will also change your toe, or
tracking.

--
Mike F.
Thornhill (near Toronto), Ont.

Replace tt with t (twice!) and remove parentheses to email me directly.
(But I check the newsgroup more often than this email address.)

 

[jg]

I had new tyres fitted a few years ago to my '87 740, and at the same
time had the tracking (toe-in) set. The front tyres wore down on the
outside edges far more than the rest of the tread, so I had the
tracking rechecked at a different place.

You've gotta stop driving down sewer pipes. The front tyres on most cars I
have had wore that way to some extent (including the current 1980 volvo).
With age I would expect it to develop toe out but that doesn't seem to stop
wear on the outsides. At least I've saved quite a lot on alignments by
practically never doing them - 99% of my tyre problems were caused by the
tyres themselves.

 

[Stewart Hargrave]

As just said in another thread, different tires are different. Maybe
these tires need a little more air.

It doesn't seem to be characteristic of under inflation. I would
anticipate wear on both edges in this case.

Camber can be adjusted...

[..]

Right, I'll find me tape measure.

I had thought this was only possible on the 240; I thought the top of
the suspension tower of the 740 was non-adjustable. I've just read
Stephen Ringlee's well known 700/900 FAQ, which has details of
re-drilling or slotting the tower bolt holes, which sounds like a
practical idea.

Thanks for the details.

--

Stewart Hargrave


For email, replace 'SpamOnlyToHere' with my name

 

[Stewart Hargrave]

You've gotta stop driving down sewer pipes. The front tyres on most cars I
have had wore that way to some extent (including the current 1980 volvo).

Thinking about it, it may in fact be a function of the excellent
steering lock these cars have. Manouvering into and out of tight
parking spaces every day, even at dead slow speed, may scrub the outer
edge of the tyre.

With age I would expect it to develop toe out but that doesn't seem to stop
wear on the outsides. At least I've saved quite a lot on alignments by
practically never doing them - 99% of my tyre problems were caused by the
tyres themselves.

Checking the alignment is usually a freebie around here, but as soon
as they get the spanners out it's 30 quid. When I replaced the track
(tie) rods I made a rudimentary jig to measured the length from
knuckle to ball joint centre, and set the new ones to the same. To my
satisfaction, it was within tolerance when it was checked.
--

Stewart Hargrave


For email, replace 'SpamOnlyToHere' with my name

 

[Peter K L Milnes]

The only other cause could be to do with the bushes on the front suspension
arms. When they get worn they affect the tracking but only dynamically (car
on move not stationary).

Cheers, Peter.

 

[jg]

Thinking about it, it may in fact be a function of the excellent
steering lock these cars have. Manouvering into and out of tight
parking spaces every day, even at dead slow speed, may scrub the outer
edge of the tyre.


Checking the alignment is usually a freebie around here, but as soon
as they get the spanners out it's 30 quid. When I replaced the track
(tie) rods I made a rudimentary jig to measured the length from
knuckle to ball joint centre, and set the new ones to the same. To my
satisfaction, it was within tolerance when it was checked.

It's free here too sometimes, but how many you reckon they find which don't
need it?

 

[Mike F]

It doesn't seem to be characteristic of under inflation. I would
anticipate wear on both edges in this case.

What I mean by "different" is in the stiffness of the sidewall, or even
the whole tire may allow it to "roll over" a little more during
cornering than is optimum for the 740s particular suspension design.
Adding a little extra air will support the tire a little better, keeping
the wear more even.

--
Mike F.
Thornhill (near Toronto), Ont.

Replace tt with t (twice!) and remove parentheses to email me directly.
(But I check the newsgroup more often than this email address.)

 

[jg]

Thinking about it, it may in fact be a function of the excellent
steering lock these cars have. Manouvering into and out of tight
parking spaces every day, even at dead slow speed, may scrub the outer
edge of the tyre.

Could be, but I suspect it's just the pressure on the outer front wheel
round corners, especially its outer perimeter right at the fulcrum. I have
no experience with other volvos but my 1980 wagon really handles like a pig
round corners but so nice otherwise I forgive it. It's quite narrow & off
the ground too & it all adds up to body roll and wear on the outer edge of
front tyres.