Proper application of tire tax credit

​​​​​​​We are a trailer dealer. We want to take advantage of the tire tax credit under Section 4051(d), but we are not sure how the credit affects our calculation of the Section 4051 tax. Do we deduct the credit from the sale price or from the Section 4051 tax or from some other amount? Also, in certain transactions, we may want to give our customers a discount of the amount equal to the tire tax credit. In such cases, how do we calculate the Section 4051 tax?