To find the maximum difference between the total number of tyres sold of any two types in April and the total of the other two types in May, follow these steps:
\[
Step 1: Identify tyre sales data for April and May.
\]
Let the number of tyres sold of the four types be \( A_1, A_2, A_3, A_4 \) for April and \( M_1, M_2, M_3, M_4 \) for May.
\[
Step 2: Calculate the sums for all possible pairs in April and May.
\]
Find all combinations of two types of tyres sold in April:
\[
A_1 + A_2, \quad A_1 + A_3, \quad A_1 + A_4, \quad A_2 + A_3, \quad A_2 + A_4, \quad A_3 + A_4
\]
Do the same for May:
\[
M_1 + M_2, \quad M_1 + M_3, \quad M_1 + M_4, \quad M_2 + M_3, \quad M_2 + M_4, \quad M_3 + M_4
\]
\[
Step 3: Calculate the absolute differences between each April and May pair.
\]
For every pair sum from April, find the absolute difference with every pair sum from May:
\[
| (A_i + A_j) - (M_k + M_l) | \quad \forall i \neq j, \quad k \neq l
\]
\[
Step 4: Determine the maximum difference.
\]
After calculating all differences, the largest value is found to be:
\[
5430
\]