Don't think it matters who mounts them as long as they balance and torque correctly. Nokian makes a superior winter tire. Not looking at data manuals...to be sure they offer the correct size...they make a WR that is sufficient for running all year round but especially perform well in snow. This company is based out of Finland and they use an advanced silica compound that really seems to work well. If I were going to drive my SLK in the snow I would put some Nokians to the road. I shouldn't plug this brand being that I don't sell it...so make no mistake that I have any sideline agenda. Just think they make a good product.