I started with new car sales volume and forgot to account for service department tire replacements until pretty late.
Break down the problem into the number of new and used cars sold annually, then estimate the number of tires per car (including new car tires, replacement tires, and spare tires). Use a top-down approach starting with the dealership's sales volume, then apply tire-related assumptions.
Pro tip: Clearly state your assumptions and round numbers to make calculations easier; interviewers care more about your structured thinking than exact figures.
Confirm what 'purchases' means: tires bought for new cars, for used car reconditioning, for replacement sales, and for service. Also clarify if the dealership is large and in San Jose.
Estimate the number of new and used cars sold per year. For a large dealership, assume a reasonable number, e.g., 100 new cars and 150 used cars per month, totaling 3,000 cars per year.
Each new car comes with 4 tires plus a spare (if included). Used cars may need 4 new tires for reconditioning. Also consider that some new cars may have tires replaced before sale due to damage or upgrades.
The dealership's service department sells replacement tires to customers. Estimate the number of service visits per year and the percentage that include tire replacement, then multiply by tires per replacement.
Add up all tire purchases from new cars, used cars, and replacement sales. Sanity-check the total against the dealership's size and local market.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.