My neighbours, Tallyho69 are right. From San Blas to Tepic is a serious grade. Not only that, the road is narrow with lots of overhanging trees.
We have no recent knowledge of the road conditions on this route but we used to use it regularly in a 30' gas Class A motorhome (widebody) towing a Chevy tracker:
From the intersection of the road from Las Varas and the Tepic-San Blas road, turn LEFT towards San Blas(instead of right towards Tepic) Just across the bridge, turn RIGHT towards Guadalupe Victoria. On the Guia Roji it's a yellow road but it used to be quite good. Depends on what Manuel did to it. (Actually, we wouldn't mind finding out how the road is this year, will go that way if not washed out!) This is flat all the way. Watch out for vados (dips in the road to allow flood water to clear).
Don't know where he is but there are very competent mechanics in Mexico, particularly in the big cities. For instance, I'm sure he could get it attended to in Puerto Vallarta.
From Guadalupe Victoria turn right, through Villa Hidalgo and on to the libre. Follow the libre until you can connect to the toll road.
At the little village of Matachén, (before San Blas) don't miss the shops along the road selling the most magnificent banana bread and other goodies. Just watch out for the jejenes (tiny biting flies!)
