Heavy duty freight truck maker Navistar has lowered its industry production forecast for fiscal 2008 ended October 31st 2008.

Demand for the medium and heavy trucks in the US has plummeted this year.

Truck buyers stocked up on vehicles during the final months of 2006 because they wanted to avoid federal clean-air rules that went into effect Jan. 1, which obliged truckmakers to install higher-priced, low-emission diesel engines.

As a result of the 2006 'pull-forward' truck sales fell sharply in the first months of 2007 and the expected rebound has failed to materialise,

Just a month ago, Navistar predicted industrywide retail sales of commercial trucks and school buses would reach 328,000 for its fiscal year ending Oct. 31, 2008. But now the company thinks sales will more likely be in the range of 303,000 to 328,000.