My SLK 55 has 17X 7.5 in wheels in front and 17X8.5 inch wheels in back, my question is- can I go with 4 of the same snow tires or should they be staggered in size to reflect the OEM tire sizes.

1. If you keep the same size you need to make sure the rears have the same OD as the OEM tires. This is because your odometer will be off otherwise. But if you do this you may end up with the front tires not having clearance.
2. I would have thought that the owners manual would address this - or at least the dealer should have info.

Like being able to rotate the tires from front to back to extend the tire life. Also, narrower tires cut through snow and slush much better.

The 225/45R17 tires fit both the stock front 7.5" and stock 8.5" rear wheels. The look will be slightly different, but this is more effective in snow, more choices are available in the 225/45R17, and you'll find this type of setup is more economical than trying to stagger the snows.<ul><li><a href="http://www.tirerack.com/a.jsp?a=AR8&amp;url=/winter/index.jsp">winter</a></li></ul>

Also thanks for your company's superior level of service.

and thanks for the compliments! Feel free to call me direct or refer to 'gary/audiworld' if you order online.