Tyre/handling

I'd guess some part of the suspension is misaligned, and the original tyre was worn to it. The 'new' tyre is probably not contacting the road evenly.

Ideally both tyres on an axle should be the same make and type, with similar wear. IOW the diameter should be the same. The characteristics of a tyres from diferent manufacturers can vary quite considerably. A different level of grip, flexibility, slip angle etc. Odd tyres, especially on the axle of a FWD car, can mean in effect that the tyre on one side is fighting the tyre on the other side. Under the stresses of cornering, acceleration and braking etc, they are not both reacting in the same way. You are seeing the results of such a mismatch. Mike.

presumably though the car is a sierra and would be Rear Wheel Drive in his case.

most likely is that a bush is gone, either a/r bar or tca probably, it should be obvious on inspection, less likely but still common is a bent strut or faulty top mount.

FWD or RWD the affects of odd front tyres on steering, cornering, and braking etc would be similar

That could certainly be a cause of the uneven tyre wear, but I don't think it's the cause of his imprecise steering problem. Mike.

IME the effects of different sizes and types of tyres on each side make little difference to the handling of a car as far as the average driver is concerned. Yes, it makes a difference when you try harder, but ordinarily, no.

something with play or a flat tyre will make a big difference.

it could even be a track rod end with play, but a TCA is a pretty common problem on a sierra and would fit with the tyre wear

No one has mentioned the obvious which is that he's replaced a decent quality worn tyre with a remould or crap tyre made in Itchifanni with more tread but no grip. The suspension problem which has scrubbed the tread off the first tyre obviously still needs to be addressed.

I think you'll find my first post covered that point.

The suspension problem which has scrubbed the tread off

And my 2nd post made a similar point about the uneven tyre wear. Mike.

IME a bent or loose suspension link causes much more noticeable steering defects, especially at low speeds.

Once he's got that fixed I would recommend decent tyres that are matched across axles anyway-- even if you don't plan on driving fast it's safer for accident near-misses.

I have not yet had a chance to drag the trolley jack out change the tyres around what with the bad weather, but have had a look at all the tyres and found two are identical and intend to put both of these on the front.

At the moment, the identical tyres are on the front off side (the one I swapped) and the rear off side. None of the tyres are top brand names. The identical pair are Toyo 185/65 R14 86T. So I presume not that budget as rated to118MPH (standard is R 106MPH for my Sierra 1.8LX 1990). The other two are both of Russian origin. Both say 185/65 R14, but no three digit weight/speed rating number that I can find. Since looking into this in detail, I am getting slightly concerned about both those tyres. The tread is like new and I didn't give them a second look apart from an occasional check for wear. The handling was so good and so didn't prompt futher investigation. However, if handling returns to normal, I think I'll be happy with them on the back. There is a big difference in the look of the tread of both the front tyres as it stands at the moment and I suspect this is not helping and got high hopes putting identical tyres on front will cure the handling problems.

I understand all that has been said about the uneven wear on the old tyre I replaced and that it may be due to the Track Control Arm or a worn bush, but I do a very small amount of miles and it will take a long time to wear the replacement tyre and must be remembered handling was superb before the tyre swap. Its not been bashed up kerbs or any mistreatment. Track rod ends are ok as I know how they feel when worn. There is not any play in steering or wandering and it drives perfectly straight. Just, since changing the tyre, it can loose the line of a corner once in a while. Its only when cornering left at speed where it will loose the line of the corner and needs correcting (dry road). All of my driving is either motorway or fast A roads (A11/M11). Sometimes on motorway when changing lanes left, it feels the same as struggling with cross winds when over 75.

Anyway, I'll swap the tyres and report back.

Thanks for everyone's thoughts and opinions about this. Graham