Sorry if this has been asked before but I have just had a dicey drive home in the first half reasonable snow we have had since getting my GLE 250d AMG in Sept 16. When I stopped on my lightly sloping driveway the car started sliding even with the handbrake on. Checked tyres and to my surprise are nearly down to the wear indicators on the front and not much better on the rears. My previous car an E350d AMG did 30,000 miles on original tyres, I have driven 11,000 on these and am a steady driver. Does this wear sound normal? Thank you.