Front tyre wear, outside edge

[Dieselman]

Just as a "heads up" guys since i see you are heavily into the math now.... The issue regarding the pull is not nececerally the actual camber/ castor positions it's the disparity between them over the axle.

I was working out the rear camber angle for rear tyre inner wear, not the original pulling issue.

We like string..

 

[Number_Cruncher]

>>Am I doing this wrong.?

Bluntly, yes!

With the lower edge of the spirit level on the rim, and measuring the distance from the top, the spirit level is forming a radius, pivotting at the lower edge of the rim, not a diameter.

So, if the spirit level were to sweep out a full circle, it would be a 32" circle, not a 16" one. From then on, your approach would give the right answer.

 

[Dieselman]

Thanks. I kept thinking about that when first writing it.

 

[Number_Cruncher]

>>Although i'm yet to see castor measured with string or spirit levels i'm sure it's possible!

By making repeated camber measurements with the steered wheels at known steer angles, the castor can be extracted from the measurements by finding the rate of change of "camber" with respect to the steer angle.

 

[wheels-inmotion]

>>Although i'm yet to see castor measured with string or spirit levels i'm sure it's possible!

By making repeated camber measurements with the steered wheels at known steer angles, the castor can be extracted from the measurements by finding the rate of change of "camber" with respect to the steer angle.

Clever stuff, seems very time consuming but i can see your method.

 

[Bazzle]

You can measure camber reasonably accurately with a virticle spirit level and tape measure or a plumb bob and piece of board to make a camber gauge.

I use one of those digital spirit levels to do mine, front and rear.

Bazzle

 

[Bazzle]

With Merc 07 car im sure the current tyre wear will always make it pull to the left now. I would swap front wheels over and see if it improves.

On my SLK I have directional tyres (Yokos) I swap the tyres off the rims to the opp sides every 10k or so to even out the camber wear.

Bazzle

 

[msb]

Thanks guys for your help on this, really helpful , if it wasnt for the maths! (not my strong point), I've got 17" rims, so what measrementdo I need, or it is simplay a case of replacing the 16 with a 17?

Thanks again.

 

[Dieselman]

For a 17" rim the figure is 7.53mm per degree.

 

[msb]

Dieselman, brilliant thanks very much for your help!

 

[merc07]

Well just as an update, Wheels In Motion did a great job.

At 41500 miles, the fronts have now done 22k. They are both wearing evenly and still have 4.5mm of tread left.

I have just replaced the rears, again 22k, they were down to 1.6mm pasenger side, 2.0mm drivers side, fairly even across the tread.

I rekon my driving is 75% short town stop start, 25% motorway.

Cheers
Adam

 

[skymastor]

I have now got Koni Yellow gas adjustable front and rear sports shockers with PI lowered springs and Continental ContiSportContact 3 tyres all round on my W203. The ride is now amazing and the tyre wear and pulling to the left seems to have gone from the original set-up..

It'll do for me.....

 

[wheels-inmotion]

Well just as an update, Wheels In Motion did a great job.

At 41500 miles, the fronts have now done 22k. They are both wearing evenly and still have 4.5mm of tread left.

I have just replaced the rears, again 22k, they were down to 1.6mm pasenger side, 2.0mm drivers side, fairly even across the tread.

I rekon my driving is 75% short town stop start, 25% motorway.

Cheers
Adam

Excellent.... You just destroyed the dealers myth that they "all pull" and they "all wear like that"....

 

[hawk20]

Good explanations here

Wheel Alignment A Short Course

What a clear and easy to follow article. Thanks.

 

[cozzykim]

Sorry to resurrect such an old thread

I have a CLK 270 which wears the outside front tyre edges, the nearside slightly more than the offside.
The last inch of offside tread is completely gone while the rest of the tyre has around 4-5mm on it. (The tread depth increases rapidly away from the tyre edge).

The suspension alignment has been checked independently by three different local garages (although not by MB or a specialist of WIM's standing)
The alignment is within spec, in fact the toe in is at the lesser end of the spec (i.e. any less would be erring towards toe out) and the front tyres have done 12-15K miles.(Contisports)

One of the local garages has suggested that I should allow them to adjust to give less toe in to reduce the problem, if this is a reasonable approach then how much adjustment should be necessary to achieve less aggressive tyre wear?

For the last 3K miles I've been running with slightly higher tyre pressures on the front (around 34psi) and slightly lower on the back (around 30psi) as my rears also have the well known problem of higher wear in the centre. The rears aren't so bad at about 1mm difference, they were on their way out anyway after around 25K

Increasing the front pressures seems to have slightly reduced the edge wear as suggested earlier in this thread but having bought a full set of new wheels/tyres I want to make some pro-active attempt to improve the front wear characteristics.

Interestingly the garage have another customer with a CLK 270 of similar age which doesn't appear to have the same problem

Does anyone have any suggestions how much less toe in adjustment would help?

Thanks