GM is planning to suspend truck production at its three pickup assembly plants for 10 weeks across 2013 as it prepares them for the launch of its new generation of trucks, including the Chevrolet Silverado and GMC Sierra models, due for rollout in the second quarter of this year.

The company is switching from its GMT900 truck architecture to the new K2XX architecture, a move that involves a complex production changeover at the Flint, Michigan, Fort Wayne, Indiana, and Arlington, Texas plants. Taken together it will mean intermittent closures totaling 21 weeks.

Its truck plant in Silao, Mexico will introduce closures in 2014.

To ensure there is sufficient supply of trucks to cover that period, the carmaker has built its inventory of trucks up to a 117-day lead, up from 80 days at the end of December last year. At the end of January the company had 239,000 full size pickups ready for supply compared to around 221,000 in December.

Inventory levels for all vehicles stood at 95 days at the end of January, amounting to almost 738,000, compared to a lead time of 76 days in December when figures stood at just over 717,000.

The carmaker was keen to stress that it was not overstocked or contending with any inventory problems. It reported that full-size pickup sales were up 32% to 50,230 units in January and said that inventories were in-line with the company’s sales and production plans for 2013.

“We have been carrying higher stock levels than normal for about a year because of the downtime required to prepare our plants for the launch of an all-new generation of GM trucks starting in Q2 2013,” a spokesman for GM told Automotive Logistics News. “Last year, there were about 29 down weeks in our truck system to prepare for the launch. This year, there will be another 10-weeks or so to complete the changeover across all of our pickup truck plants.”

GM said it was unable to comment on how the rise in inventory and the production downturn will affect its outbound logistics schedule, but did say that the sales and production plan is designed to ensure a smooth transition from today’s Silverado and Sierra trucks to the all-new designs over the course of 2013.

The company said it was not contemplating any changes to production.