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Dr. Den · 06-07-2014, 05:45 PM

Just wondering . . . headed west for my first time and it looks like going through Colorado there are several passes listed. In a gas Class C, what road grades do I want to avoid, 5% / 7% / 10 % . . . . . also keeping in mind, what goes up, must come down.

BFlinn181 · 06-07-2014, 06:50 PM

Interstate specifications are to be no more than 6% with a few exceptions. In CO there are a few of those, Wolf Creek Pass is 6.8%, approaches on I-70 to Eisenhower Tunnel is 6%, further west on I-70 Vail Pass is 7%. If you really want to know what's down the road, the Mountain Directory is a good reference book.

Mountain Driving Guide for Truckers, RV and Motorhome Drivers

Driving in the mountains requires paying more attention to RPMs and temperature gauge than flat driving. Downshift when temp starts to climb, not when the transmission decides. Higher RPM means cooler engine because it's using maximum torque and horsepower instead of 'lugging' the engine. It also circulates coolant faster to keep things cooler. Don't worry about speed, use your flashers if you drop below 40 mph. Going down, also downshift and only apply brakes firmly and quickly to drop speed by 10 mph or so. Then FOOT OFF BRAKE PEDAL until you need to apply again to drop 10 mph. I assume you have supplementary brakes in your Wrangler, if not, get them. An un-braked car pushing you down a hill is dangerous.

Gordon Dewald · 06-07-2014, 07:13 PM

You should have no problems. Drive very conservatively.

UPHILL - Accelerateas you approach the bottom of the hill. Carry the speed as far as you can and then when the vehicle starts slowing down downshift to a lower gear to keep the RPM up. If you know the RPM of your maximum torque and HP shift down when the new gear brings your RPM up close to that RPM or a little more. You may have to shift a couple times but eventually you will get to the top of the hill.

DOWNHILL - As you approach the top of a hill slow down and shift down to the same gear you came up the hill in. Ease off the throttle and let the vehicle coast down the hill. Look ahead and if it is still steep brake crisply (apply firm pressure to slow down) to scrub off around 10 mph. If you have to use the accelerator to maintain speed you may want to shift up a gear.

A lot of this is common sense and observing how your vehicle handles. Mentally note the grades and how the vehicle handles them. Modify your actions to get the best performance. Be cautious and learn from each hill you climb or descend.

As you get to the bottom of the hill shift into overdrive to coast out onto the flats if it is safe. (Dont do so if you can see a tight curve ahead or there is slow traffic ahead.) You should be close to your travel speed as you coast onto the flats. All you have to do then is add accelerator to maintain the speed.

You will have to experiment to learn your vehicles characteristics. Experiment on the conservative side. Observation is your biggest tool for learning. Look at the road, the signs, the temp gauge, gear selection and how the vehicle 'feels' and handles.

Everybody I know was a new driver in the hills at one time.