As reported in this month’s Guidelines (to be released shortly), the average retail selling price of 4-year-old sleeper tractors has been flat since the beginning of the year. Average mileage has steadily increased throughout that period, which at least partially explains the lack of upward movement. The other likely explanation is that at $60-$65K for a truck with well over 400,000 miles, buyers are finding it easier to make a business case for moving to a new truck purchase or lease.

More evidence of a price ceiling lies in the wholesale market. While 4-year-old trucks were flatlining in the retail market, price and mileage were returning to their traditional inverse relationship in the wholesale market.

In statistical terms, the correlation between wholesale price and mileage from January to December 2010 was 0.11, indicating essentially no relationship. From January to July of 2011, however, that figure drops to -0.79, indicating a strong negative relationship.

Based on this recent data, we can now begin to judge how high mileage must get for buyers to hesitate. From January to March, buyers were paying elevated prices for trucks with mileage in the low-600’s. Prices started to dip when mileage climbed through 650K in April, and continued that behavior through June. Then, in July, mileage fell back towards the low-600’s, and price turned back around.

At this point, then, it appears that the mid-600K range represents a price delineator. This is logical seeing as maintenance and repair costs hit their next tier at around that mileage.

This is not intended to be a definitive study. We “clean” our data each month, but age and spec mix of trucks is not identical from month to month. And external economic factors may influence buying decisions at any given time. However, the data does paint a compelling picture about mileage tolerance for 2011 to date.