A lesson in fitting tyres in pairs

[Randy]

My recently purchased Ghibli was pulling right quite badly which obviously somewhat impaired the driving experience so I set about curing it straight away. The car has been treated to some work on the steering system recently so I can only assume that the problem has been ongoing and people have been attempting to remedy it (unsuccessfully).

A 'quick and dirty' geo revealed the tracking to be out and also some misalignment of the rear subframe. With these bits straightened out she was a little better but still pulling to the right quite badly. The corner weight scales had revealed 20kg across the front axle and given the very balanced static weight distribution on the car this told me that something was wrong. Possible culprits were a broken spring, sagging spring, defective damper or an issue with the tyres.

The front tyres were odd side to side so I pulled them off for measurement. Despite both being 215/45/17 the actual sizes were dramatically different both in diameter and width. With my background I'm familiar with tyres from different brands coming out in different shaped/sizes but I wasn't expecting such a massive difference. Here are the pictures showing the problem. Now, with a pair of new tyre fitted, the car drives beautifully and no longer pulls to the right

So, lesson to all... Remember to change tyres in pairs and if possible use the same type/brand all round!

 

[CatmanV2]

Well that's new (for me, at least) Every day's a school day!

C

 

[Parisien]

It looked as if either improperly inflated, tracked of balanced...maybe all three!

P

 

[Randy]

As pictured, both tyres were at the correct and equal inflation. Tracking was out (although no by an order of magnitude) and they were scrubbing because the car was pulling with the different OD.

 

[CatmanV2]

That one on the right doesn't even look square to me.

C

 

[2b1ask1]

Ditto Catman it is conical but not comical!

 

[Randy]

These tyres must have been on the car scrubbing away for a good few thousand miles. Makes me wonder whether it was one of the reasons the previous owner sold the car, maybe they tried working on the steering to get it fixed, failed and decided there must be something seriously wrong?!

 

[TridentTested]

These tyres must have been on the car scrubbing away for a good few thousand miles. Makes me wonder whether it was one of the reasons the previous owner sold the car, maybe they tried working on the steering to get it fixed, failed and decided there must be something seriously wrong?!

Quite possibly.

On my last car the main dealer changed my front bearings under warranty - a very expensive procedure involving new ABS sensors et al - it was only later a small indie correctly diagnosed the problem was the tyres being slightly off-round; the car had obviously been parked up for a while before I bought it. I got the supplying MD to change these, under warranty thankfully, and the problem was cured.

 

[Ewan]

I had Dunlop Sports on my Ghibli - fine in the dry, but shocking in the wet/cold even with plenty of tread. Swapping to Goodyear F1 Assymetrics made an enormous difference. It's certainly a car that needs the appropriate tyres.

 

[bigbob]

Quite possibly.

On my last car the main dealer changed my front bearings under warranty - a very expensive procedure involving new ABS sensors et al - it was only later a small indie correctly diagnosed the problem was the tyres being slightly off-round; the car had obviously been parked up for a while before I bought it. I got the supplying MD to change these, under warranty thankfully, and the problem was cured.

It's a big issue with cars like Maserati in that they can sit in showrooms for six months every two years or so on low/correct tyre pressures.

 

[mjheathcote]

Or six months over winter.
I take my stag off the road over winter and pump the tyres up to 50 psi.