I don't think I-10 runs into I-40, it runs out through el paso, across NM, into AZ and then CA. This time of year, I would follow I-10 to Blythe , Ca , then take US 95 N to I-40 at Needles , Ca , then I-40 W to Barstow , Ca , Then Ca 58 across to Bakersfield , Ca and on to Button willow , Ca at I-5 , Then continue up I-5 to Washington. The pull from Needles up to South Pass , is about the hardest one on this route. One pretty good pull on hwy 58 at Tehachapi , Ca. Not a bad trip, and quite scenic for this time of year. Best wishes , and God Bless ya, Al & Dee Weaver