I'm looking for solution to assist winter traction. I run Goodyear 235/45-17 UltraGrip GW3 on my stock rims and usually put 150# of sand (3 plastic bags) in the trunk. I've had no problem in 2-winters --except worrying about what the bags do if I end up in a big spin. I was thinking of using a layer of small interlocking paving stones. Any suggestions?? Thanks.