Thor Industries Inc. gained the most in three months after the maker of RVs and buses said sales surged 30% to a fiscal first-quarter record.

Bloomberg reported that Thor shares climbed 12% to $44.96 in midday trading after advancing as much as 14%, the most intraday since Aug. 3. The Jackson Center, Ohio-based company’s stock had risen 46% this year through yesterday.

Sales for the quarter ended Oct. 31 rose to $876.8 million, Thor said in releasing preliminary results. The average of analysts’ estimates compiled by Bloomberg was $745.5 million. Thor said in a statement that its order backlog at the end of October was $720.4 million, up 41% from a year earlier.

According to Bloomberg, sales of recreational vehicles are monitored as a sign of an improving economy because motorhomes and travel trailers are discretionary purchases that consumers defer during a slump.