Do I need matching tyre sizes on my Evo?

[StottyEvo]

I have 225/40/18 on the rear, I've just had some 235/40/18 fitted on the front. Will this kill my diff? If so I won't be driving it until I get a full new set of tyres...

I've just give it a bit off a couple of roundabouts and the steering feels snatchy, not very confidence inspiring.

[DAVEVO9]

Same size rubber all round sir.

[StottyEvo]

Thank you. Kicking myself now, the tyres were slightly stretched so I thought I'd get the proper size put on the rims (bought the car that way) then realised once I'd left the tyre house!