How many miles on your 315s
 

It looks like I cannot go more than 30000 km on a pair of 315s. There is no play in the rear suspension, I replaced the wishbones and links and did an alignment. The inner side is worn out The mechanic says it's normal. How normal is this?

are they wearing evenly across the tread???

if they are then your next option is to look at the wear rate number

i think the lower it is the softer the compound the quicker they wear

i presently have Arturos with a wear rate number of 400 (+ i think) and have done 30,000km and they look less that half worn, however i travel mostly freeway so little chance to go screaming around corners

back awhile the bridgestone potenzas had a reputation for wearing out quickly, a very soft tyre compound

but they stuck to the corners like glue

so first check your tyre type and softness factor that might explain it all

Alignment has a ton to do with it. I put my new X5 on our Laser Rack and was pretty amazed at the results. Here's a link:
Why would you align a Brand-New car? Here’s Why. | Edge Motor Works

I am actually kind of pissed at the fact that the front end is out of spec and there is no way to fix it short of running one of the different length arms. Anyway, glad I aligned it as it handles much better and should be alot easier on the tires.