AWD Tyre depths - replacing a pair.

[texaxile]

Car is a 2004 WRX Impreza, 127k fully standard but with new bushes all round and replaced suspension 1k ago.

Mileage is 50/50 A roads and dual carriageways, 4k pa.

Tyres have 5.6mm tread all round.

I've managed to pick up a puncture on my car, so need to replace as it's sidewall. I'm happy to replace both on the same axle and keep the good one back as a spare, but there will be a 2.4 mm difference in tyres on the rear to the front.

My question is as the Impreza is permanent AWD, will this much of a difference bugger anything up?.

as it's an old car now, 127k gives a bit of "slop" in the drivetrain , I'm hoping it won't really matter too much, but I don't know enough to make that call.

[E-bmw]

Difference between 5.6 & new (I would think) would not matter it is only going to be perhaps 1% or 1.5 different front to rear.

[sam.rog]

You will be fine with that difference.
My Impreza wears the rear tyres quicker than the fronts due to the dccd diff and never had any issues.