I promise this is my last question....altitudes along I-90

I've never noticed any hills on I90.
I wouldn't worry about it. ;)

EDIT: Sorry , I see you may need 02. THe hills aren't bad - a few thousand feet.

You shouldn't have any problems - just a short downgrade from the pass to Whitehall. Just slow down a bit and stay in the right lane with the trucks. As far as passes go, this is a little one.

Just checked the West Mountain Directory and the only REALLY scary part is Homestake Pass. I guess there's no way of avoiding that, huh, unless I go north on I-15 to Helena then going back to I-90 via 287.

Penny, you're not being a pain. :) Haven't done the entire route on 90, but at least from Missoula east, I don't recall any altitudes or grades on 90 worth worrying about - even 80 is higher, and 70 is the one with all the really high altitudes and long climbs. I think you'll be fine. Probably the biggest climb you'll have on 90 will be just east of the Seattle area.

PennyPA wrote:
Oldman, I have the West Mountain Directory but thought people here would be helpful.

Your question was 'what altitudes will I be looking at?'

You must be looking for more help than that.

Jeep, I have a 2001 Dodge 3500 with a 4:10 rear. Towing about 12500 lbs. Automatic. Already has an exhaust brake. Going through there in July/August. I'm also concerned because I need O2 at altitude.

Also, read the wiki link and didn't really learn much there except there are higher altitudes along other routes.

Oldman, I have the West Mountain Directory but thought people here would be helpful.

You will not have any issues getting over the mountains with your rig. Just enjoy it and have fun!

Wiki link
http://en.m.wikipedia.org/wiki/Interstate_90

Your signature doesn't mention what year Dodge diesel you own. I also have no clue what kind of weight your towing with what tranny? Altitude doesn't mean as much to a diesel engine. Gas engines are severely affected by altitude. What time of year? If not Summer, by good chains ahead of time. If an option get an exhaust brake.

A must-have for mountain drivers is this....Mountain directory books

Well worth the price.