In my experience tires are not a huge margin item, so you need to move a lot of them in order to be successful. Wearables like tires, filters and friction products are tough because of how many people are in the market selling them. It takes a real salesperson to show value in the service and close the sale when you're not the cheapest kid on the block.
Unfortunately the workforce is drowning in meer "order takers", not salesmen. if you don't have ordertakers working for you, then you could be successful. If you do, either sales training/couching is a must before introducing a new product line. I'm dealing with this right now myself.
Best of luck.