Have you got the receipt? Does it specify the tyre size. Check it against the size the car should have. If it is wrong, simply go back, point it out and say that unless they supply a new tyre of the right size FOC, you will on to Trading Standards, the local press, Facebook and the regulatory body under which they operate.

Having run over something sharp I went to a supposedly reputible supplier to change my front passanger side tyre, whilst I was there they kept asking if I wanted tracking, weights on my tyres checking etc and I ended up paying £100 for a new budget tyre and the 'other' jobs! 10 weeks later, I'm driving into work and I feel my steering go- like you're on ice but I wasn't on ice. I damaged the back of my car and ripped the back tyre as my steering had just jarred and I couldn't avoid it. When I went to get my back tyre changed at a different garage (which only cost £45 for the same tyre), they asked me why my front left tyre was the wrong size?! The company had fitted a tyre 10mm smaller than my other tyres. I contacted the company and they asked me to get a quote for the work, said they accepted liability and told me their insureres would be in contact. However, then I receive a letter saying they don't accept liability! How dangerous is it to fit the wrong size tyre?

Technically, when changing tyres, as long as they are allowed by the car manufacturer (only certain sizes and minimum speed ratings are allowed), different combinations of wheel and tyre sizes are possible, as long as you stay within 2.5% of the rolling circumfrence (or diameter) of the other tyres.

That being said, they, in my view, have no excuse when replacing a tyre on a like-for-like basis - it must match the existing tyre on that axle exactly in specifications, including the tyre type (i.e. directional, asymmetric or none of those) to make sure the car handles properly, especially in poor weather. My first point only pertains when you are changing wheel sizes, i.e. bigger (or smaller) alloys.

Obviously a brand new tyre with 7mm tead across the width of the tyre will be 10mm larger in diameter to a worn tyre (of the same spec) with only 2mm of tread left. I would confirm the size of the tyres first to see if that wasn't the case - I suspect it isn't, as the tyre size is easily noticeable on the sidewall facing outwards.

The bit you need to check is where it says (for example): 205/55 R16 V

• 205 (in mm) is the width of the tyre;
• 55 is the height of the tyre sidewall as a percentage of the width, in my example it's 205 x 0.55 = 112.75mm;
• R16 is the diameter of the wheel in inches (1in = 25.4mm)
• V is the speed rating of the tyre (max 149mph in that case - this can be higher than the original, but cannot be lower than any other tyre fitted to the car at one time)

Don't forget that the overal diameter is equal to the alloy wheel size plus 2x the sidewall height (each side of the wheel). Don't be fobbed off by a fitter saying that its ok to fit a wider tyre with a lower sidewall ratio, even if that matches the other tyre's rolling diameter to within 2.5%. That's not allowed on the same axle. It is OK on different axles, i.e. you can have two matching wider tyres on the rear axle than on the front. German car brands sometime do this on sports models.

Firstly if they fitted the wrong size of tyre then they are at fault and should replace with the correct size, but i'd go round and check all the tyre sizes because its not beyond the realms of possiblity that the fitter replaced like for like without checking the sizes all round.

However 10mm (eg a 175 width section instead of a 165) is not much of a difference and i doubt you would feel much between the right size tyre and this one, the light feeling you suddenly encountered after some 10 weeks of presumably trouble free motoring suggests to me that you hit a patch of spilled Diesel or similar or if this was a couple of weeks ago, possibly excess road salt on a slightly damp road, which can be as lethal as ice, not helped when riding on some 'budget' tyres which are often called ditchfinders for good reason.

Not sure by what you meant when the steering 'jarred'?

As for the price difference, well tyres can vary from £40 for a cheapy to £120 for the same size in a premium make, you don't mention the makes involved, is the wrong size tyre still fitted and is the car driving ok or did you have two tyres fitted at garage number 2 ? if so i hope you have kept the wrong sized one for evidence.

Also the second garage did nothing other than supply and fit a tyre, they did no tracking or balancing of presumably the other three, which is what garage number 1 did, hence the extra £55.

Edited by gordonbennet on 22/04/2018 at 16:10