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MG MGF Technical - Uneven tyre wear

We already know we have a problem with the EPAS - the car pulls slightly to the left with the giveaway being the old 'ignition on and see the wheel twitch left' scenario.

Anyway on top of this we're getting uneven tyre wear on the inside of both front tyres and I'm not sure what to make of it.

As the EPAS fault isn't that severe yet, I've decided to postpone the trip to Mike Satur until after Christmas as my logic dictates that even though it wants to go left, all we're doing to correct this is hold the steering straight on.

So over to you lot. Could a slight EPAS fault cause this on a 2001 MGF, or could we be looking at other problems too?

Thanks.



D Forber

I am also seeing wear on the inside edges of my two front tyres, I have been advised this may be due to the wheel chamber; there is some suggestion that my 1998 Abingdon may have its suspesion set to the lowest setting.
Jon Osborne

Unless the ride height is spot on the manufacturer's recommendation, the camber will be out and you will get tyre scrubbing. Most Fs settle over the years. Check the height and get it pumped up if necessary.

Inner edge wear can also be caused by the wheels toeing out. Get the alignment checked.

Mike
Mike Howlett

The tracking geometry that MGR specified are for when the car is at 368mm ride height, i.e. in 4x4 mode. Anything below that ride height brings negative camber on the front wheels into the equation, which will increase the wear on the inside edges.

The tracking setup was aimed at making the car safe and predictable to drive, rather than making the tyres last as long as possible. Have a look at Rob's study on MGF alignment - http://www.mgf.ultimatemg.com/group2/suspension/tracking.htm

Two options exist - one is to stick with the factory settings, and accept that to get maximum mileage from your tyres the front two will need to be swapped from rim to rim half-way through their life, or the 2nd option is to have the car set to alternative geometry as listed on Rob's site. There are other factors to bear in mind - whether your car has a front splitter fitted plays a big part, as does the profile of the tyre (15" or 16" wheels).
Mike Hankin

I have 15" wheels, 205/50 x 15 tyres with lowering knuckles, ride height set at 340mm and run 28lbs on all four. After some 30000km my tyres are wearing to a nice even pattern. The tyres have done motokhanas, sprints and hillclimbs but not in the last 10000km as for competition I have changed to a track day tyre which also is wearing nice and flat. All my settings are as per Rob's site.
Andrew Regens

>> Unless the ride height is spot on the manufacturer's recommendation, the camber will be out and you will get tyre scrubbing. ... Inner edge wear can also be caused by the wheels toeing out. <<

Modern tyres are capable of withstanding the modest negative camber you get when the suspension is a little on the low side - and in fact you are absolutely right about the toe-angles; this is *the* cause of tyre wear on the MGF. Camber may exagerate the problem, but it isn't the cause.

I'd get the tracking checked - particularly the toe angles, and if the front toe-angles are within the manufacturer's range, then go for one of the alternative set ups Mike and Andrew allude too :o)

Good luck! :o)
Rob Bell

This thread was discussed on 09/10/2006

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