Different tire treads

[Speenybean]

So looking to buy a pair of slightly used Rear continental DWS 6 tires size 315 which apparently have about 60-70% tread life left for a really really cheap price. My question is if I put them on my F15 and put brand new tires on the front (same tire) would there be any issues having new tires in the front and used ones in the back? I read something about spin rate being different and wearing out AWD and crankcase. Just curious. Thanks for any help

[Wavy]

I have heard of people getting something done to the newer tires so the tread depth matches the older tires.

[Shaw]

When I was selling my X1, having different tire threads would not pass the safety test.
So I had to go and find the matching thread for the front. (only changing the front to match the rear)
Other note was that if I wanted to install brand new tires, that would also not pass the safety unless I changed the rear to brand new as well...(rear was around 80%)...
The certifier mentioned something about the vehicle being an xDrive, and so by installing brand new tires or if not matching threads , that it would damage the axle and other components (which I ddin't understand...lol).
so I finally went and found a slightly used front set (90%) for the front that were also matching thread.

[Mr.47]

OP save yourself the money, headache and get 4 new sets of tires. 60-70% thread life is not far away of been worn out especially for 315 rear tire and in AWD vehicle. Also you'll probally have noticeable tire noise and it will only get worse as it begins to wear down further, the S (snow) in the Continental DWS is probally faded out so it wont be good in snow anymore and you'll be replacing these tires in < 1yr. There is a reason this person is getting rid of the tires for cheap because the tires are worn and ready to be disposed.

[sj22]

Don’t do it. Keep the existing as spares if you want.

[alphaod]

I wouldn't buy 60-70% worn tires. If you consider a new tire is 10/32 and fully worn tire is 2/32, 60-70% you're talking just a little over 4/32" thread depth on the tires which means they are barely okay for wet performance let alone snow or anything else.