Selling Tires

We've all been urged to become full fledged tire salesmen. Probably a good idea given the statistics regarding tire shops getting 70% of their business from non-tire maintenance and repair jobs.
My problem is deciding how many tires to stock. To be able to really be in the tire business and service customers most of the time without having to send off for tires, it seems we'd have to really make a huge investment in inventory -- ($10,000 - $20,000). Does the dealership bite the bullet and make that investment?
Coming from the world of purchasing in a manufacturing environment, the trend is buying on consignment. Load your shop with inventory and pay the supplier as you sell or use their product. I can't seem to find a tire distributor who likes that idea.
I'd like some insight as to what others are doing in the area of tires.
My problem is deciding how many tires to stock. To be able to really be in the tire business and service customers most of the time without having to send off for tires, it seems we'd have to really make a huge investment in inventory -- ($10,000 - $20,000). Does the dealership bite the bullet and make that investment?
Coming from the world of purchasing in a manufacturing environment, the trend is buying on consignment. Load your shop with inventory and pay the supplier as you sell or use their product. I can't seem to find a tire distributor who likes that idea.
I'd like some insight as to what others are doing in the area of tires.