June 17 (Reuters) - CarMax ( KMX ) topped revenue estimates for the first quarter on Wednesday, helped by higher used-vehicle prices and stronger wholesale demand. 

Shares of the Richmond, Virginia-based company rose more than 5% in premarket trade.

Used-car companies have struggled to maintain margins as affordability concerns weigh on retail demand, even as the increase in new-vehicle prices driven by higher U.S. tariffs is expected to steer more buyers toward pre-owned cars.

CarMax's ( KMX ) retail gross profit per used vehicle fell to $2,177 in the quarter from $2,407 a year earlier, while its wholesale gross profit per unit was $1,046, compared with $1,047 a year earlier.

Average used-vehicle prices, however, were up 4.5% at $27,288 during the quarter compared with a year earlier. 

Quarterly revenue rose 6.2% to $8.01 billion from a year earlier, compared with an average analyst estimate of $7.4 billion, according to data compiled by LSEG. 

CarMax's ( KMX ) first-quarter profit came in at $185.6 million, or $1.31 per share, compared with a profit of $210.4 million, or $1.38 per share, a year earlier.