Please read my write-up in Pinewood Derby Rules.. The short answer is, “You need to read the rules for your particular race, as all rules are different.” Some races have simple, generic rules while other races have rules that are detailed with explicit measurements. If you have any questions about your rules, the only person that can answer them is your race manager as every race can have different rules. Further, the rules can change from year to year. In addition, some race managers do a cursory check on your car at weigh in while others might measure with calipers and use magnifying glasses to inspect axles and wheels. You need to understand the expectations for your particular race.
We would have no way of knowing your specific rules nor how your race manager inspects cars at check in.