Replacing both tyres?

[jasonh]

One of my front tyres has worn unevenly and needs replacing - and obviously I need to have the tracking checked too. My question is, do I really need to replace both? The other tyre is in good condition with plenty of tread left (I'd say about 75% of new) and I'm trying not to spend too much because I won't have the car beyond the autumn.

Some sources reckon it doesn't matter and some reckon having different tyres on the same axle is a horrendously bad idea. What's the answer?

[zadocbrown]

If you can get the same model of tyre and the difference in tread depth isn't too great, I don't see a problem. If you end up with different makes of tyre or a big difference in wear between the two, it's not quite so good.

[michael769]

Some sources reckon it doesn't matter and some reckon having different tyres on the same axle is a horrendously bad idea. What's the answer?

It makes more of a difference on the front axle, where it can affect handling. You would only really notice is in "performance" driving, and you get used to it pretty quickly.

One option is if it is a front tyre, is to swap front to back and then have the mismatched on the back.

[7db]

Is the spare a full wheel? If so swap out the part-worn to the spare and jobs a goodun.
I only ever do two at a time minimum. My rears wear quicker than my fronts so I rarely have totally new fronts with worn rears.

[Rabiedmushroom]

Is your car front wheel drive or rear wheel drive?

[jbsportstech]

Whether its a front or rear drive it makes little difference. If there good 6mm as you say (75% of 8mm new) then I would get a new tyre of same make and spec and being only a 2mm difference should matter overly in my experince. If the other tyre had a bigger difference say 3-4mm left I would have two new on that axle and decide whether the redundant tyre would be a suitable spare (If you have a full size that is).

2mm is a bout the biggest differencial that I would what between tyres on opposite sides but that just based on my experience stresseddave my be able to tell you whether it will make real difference to handling but I have never found it an issue. Also my experience of lease cars is that if it has 6mm they wouldn't pay for two replace.

[Rabiedmushroom]

Whether its a front or rear drive it makes little difference.

That's cobblers, unless you have different width wheels/tyres from front to back, or different compound.

If you have a front wheel drive car, it is safer to have matching or evenly worn tyres at the front, preferably the same make/tread, rather than the back, because you have all the drive, steering and heavy braking forces on them. Hence my question above to JasonH. It sounds like he's aiming for at least 6 months use out of the car.

[Rabiedmushroom]

Hi Dave, please can you then explain how "front tyres are perpetually trying to make you spin".
I am genuinely confused; for example how would this occur if you have a standard front wheel drive car driving in a straight line, with perfectly fitted/pressure new tyres and perfectly working brakes (same traction, new discs/pads so when brakes are applied it pulls neither to the left or right). I'm interested if you can elaborate please?

Edit - actually I can see how you could potentially swap ends in a skid with bald rears.

[Mr Cholmondeley-Warner]

Apart from when travelling in a straight line ...

as soon as you turn the steering wheel, you introduce a sideways force on the car. The front wheels follow the arc you point them into, the back ones have to absorb the sideways momentum generated by the change of direction. Imagine a very wet road, with nice grippy tyres on the front, bald ones on the back. What happens if you turn a corner?

[Rabiedmushroom]

Hi Nick, but if you had grippies on the back, baldies on the front, then in same situation surely you'd understeer? My front wheel drive cars would plough straight on. Eeek!

I'm really confused; I'm going by personal experience of running rubbishy tyres in my 'youff', advice from garages, friends and tyre fitters...

[Gareth]

please can you then explain how "front tyres are perpetually trying to make you spin"

I don't know if this is the correct answer and probably StressedDave will reply anyway, but I remember one of the car programs on TV carrying out a practical test driving a car around middlin' bend in the wet, and with different levels of tread of the rear tyres. What they demonstrated was that the back end would break away at a much lower speed if they had less grip than the front tyres. That is, the car would so into a spin very easily just from driving around a bend in the wet. With better rear tyres it was possible to go round the bend much faster, (read: normal speeds).

If you think about what is happening when you go around a bend, you are controlling what is happening with your entry speed and steering, and the job of the back tyres is stop the car sliding out and into a spin.

[Gareth]

if you had grippies on the back, baldies on the front, then in same situation surely you'd understeer? My front wheel drive cars would plough straight on. Eeek!

Thing is, that's easy to control by not head-butting the horizon when going into bends.

[Rabiedmushroom]

...but I remember one of the car programs on TV carrying out a practical test driving a car around middlin' bend in the wet, and with different levels of tread of the rear tyres.

That would have been good to see a number if tyre tread situations shown practically, and be easier to understand. Both for handling round a corner plus emergency braking

[Mr Cholmondeley-Warner]

As Gareth said, understeer is more easily controllable. It's progressive, and you can do something about it - either reduce speed, or apply more lock. If the back end goes, often it takes a much better driver to catch it.

[TripleS]

Apart from when travelling in a straight line ...

as soon as you turn the steering wheel, you introduce a sideways force on the car. The front wheels follow the arc you point them into, the back ones have to absorb the sideways momentum generated by the change of direction. Imagine a very wet road, with nice grippy tyres on the front, bald ones on the back. What happens if you turn a corner?

In most cases you'd probably go round the corner, unless you were to totally disregard the condition of your tyres.

Best wishes all,
Dave.