We needed a new front tyre on our Forester. The dealer justed asked if it was a 4x4, measured the tread depth on all the tyres and said we have to replace them all or the handling will go to pot.

Apparently, the tyres were about 3mm and adding just the new one with 8mm wouldn't do the drive train much good. Naturally I believed him as it's my wifes car and she was paying.

Is this true? Will a similar thing be necessary on my scout when the time come?

I would have thought you could get away with a pair. Personally I'd never replace a single anyway but usually I cycle my tyres every 5k miles and buy 4 at once.

Not from an iPhone

You'll get away with one pair. Lots of tyre dealers use the "it's a 4x4 you have to replace them all" trick but it is very rarely true.

However just replacing one would be looking for trouble. Would you try to walk on an icy pavement with a slipper on one foot and a walking boot on the other?

As above just replace the two on same axle. nothing to doing with handling, it's to keep the rolling circumference the same.

With the tread down to 3mm I would be considering changing all four tyres. Tyre manufacturers say tyres are less effective in the wet when the tread drops below 3mm, and I think the police routinely change their tyres at 3-4mm.

We needed a new front tyre on our Forester. The dealer justed asked if it was a 4x4, measured the tread depth on all the tyres and said we have to replace them all or the handling will go to pot.

Apparently, the tyres were about 3mm and adding just the new one with 8mm wouldn't do the drive train much good. Naturally I believed him as it's my wifes car and she was paying.

Is this true? Will a similar thing be necessary on my scout when the time come?

Having had 2 Foresters aswell as a plethora of Subarus I know that you should never change just 1 tyre, change the 2 on the same axle. As mentioned though, at 3mm tread depth I would be changing them all. Please tell your tyre fitter that Foresters are AWD not 4WD.

Only really an issue with 4x4 with LSD's from my experience on all 4. (winds the diff up and goes pop)

I'd never change just one - even on an open diff as it will effect handling. If you have to put a new one on the rear.

Boy this takes me back to the Calibra 4x4 - the handbook categorically stated that all 4 tyres had to be changed at the same time!

As the others say though, change the 2 on the same axle, and 3mm is getting to the point of no return as far as tyres are concerned.

I changed one on my scout as other three still had 6mm (had a non repairable puncture) and ran like this for 9 months until the three were down to 2mm (changed for winters at that point) and had no problems whatsoever.

Thanks guys, I won't tell her that only two needed changing, but if mine needs just one for any reason..........

Mind you, as it goes to a lot of strange fields maybe it was the right decision anyway.