Hmm...Interesting. I think you stumbled on a test case that we did not think of. Namely when all the orders are the same tire size. It is not likely going to ever happen but it is good to cover all bases.

The query is supposed to go through Table 1 grouping by dealerID and counting up all a dealers orders. This number will be the denominator in the calculation. It then looks at table 2 grouping by dealerID and by tire and dividing the count by the total orders in table 1 to get the % of the total orders. Once I have a % calculated I then need to only select the tires that make up 80% of the dealers total count, everything else is left out.