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Old 03-29-2014, 01:12 PM   #1
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Driveway Slope Grade for Airstream Interstate

I just bought a 2014 Airstream Interstate 22' and I'm going to need to redo the driveway to accommodate. The current driveway slope is fairly steep. I've attached a photo. Does anyone know the maximum grade that I can safely bring the motorhome up without bottoming out? Also, what's the maximum grade for storing the motorhome? If you don't know the right grade, how would I calculate what the Interstate can handle?
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Old 03-29-2014, 02:35 PM   #2
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We have a very steep driveway also. When we bought out 2013 Interstate EXT I cringed at the thought of trying to get it up the driveway. The departure slope is the biggest problem, so I measured from the center of the rear tire contact point, to the ground level below the lowest point behind the rear axel......the two steel rings at bumper. I then measured the height from ground to the ring to establish the clearance. That will give you the dimensions of your clearance requirement.
If you back slowly into the driveway, you will have the best chance of clearing since the rear tires will start to lift the rear end, once you get them on the slope. (Assuming you have enough clearance) If you try to drive into the slope forward, your front wheels will lift first and quickly bottom the rear in the street.

All in all....I would like to find a driveway I could enter forward.....but that would require moving. Rebuilding the driveway is not an option.

Good luck.
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Old 03-29-2014, 03:39 PM   #3
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Not sure what the storage grade would affect except for opening/closing the slider as it is a beast on anything beyond level. Might be a good question for Airstream.
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Old 03-29-2014, 04:27 PM   #4
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A Mercedes Benz press release about the 4×4 Sprinter talks about how the body is raised, and gives data for both the short-overhang 4×2 and the short-overhang 4×4. The data for the 4×2 is:

Approach angle 18°. This is the slope you can negotiate without scraping the front bumper. Airstream Interstates have a non-standard front bumper with effects molding, so it may be less.
Break-over angle 17°. This is the angle of a hump you can cross without scraping in between the front and rear wheels. Again, Airstream Interstates will be less, due to the effects molding.
Departure angle 22°. Interstates don't have effects molding at the rear, but depending on the make and model of receiver they mounted, it may be different. It will also vary depending on what you have in the receiver; even a simple hitch ball can affect the departure angle. They didn't give data for the long-overhang models.

So to answer your question about driveway angles, you're probably okay with about 15°, and you're pushing things if you go steeper. For the short-overhang Interstates, you're more likely to scrape the front bumper in the transition from street to driveway than you are the receiver, based on the data I saw. For long-overhang models, the reverse is true.
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Old 03-29-2014, 06:12 PM   #5
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Thanks everyone and great find Protagonist. I'll work within those constraints and report back on how it works.
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Old 03-29-2014, 07:27 PM   #6
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Attached drawing is three view dimensioned drawing of 2014 Sprinter 170 inch wb regular length, the base vehicle of your Interstate.

Approach angle (alpha) = 18 degrees
Departure angle (beta) = 12 degrees

You can get this drawing and other technical info at this link: Daimler Vans Upfitter Portal - Model Overview

Airstream has added body panels below the stock Sprinter body panels all around the vehicle so the approach and departure angle in the attached drawing will be less on your Interstate. The 2014 Sprinter is also an inch or so lower than the earlier models.

I've scraped my rear skids many times as I have the extended Lounge body. Some day I'm going to add a set of skid rollers under my hitch.
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Old 03-29-2014, 08:22 PM   #7
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Feel for you

We live in Atlanta and purchased our 2013 ext from Colonial in New Jersey. I sweat bullets the 600 miles back home praying I was going to have clearance in my driveway. I was lucky and the hitch has less than one inch clearance, but I can easily scrape the street it if I go up or back down to quickly. Fortunately when loaded and with full tanks it doesn't "sink" much lower. I'm not sure how to give you an idea of my grade compared to yours though.

It's hard to tell from the picture, but the brick wall on the left gives some clue as the grade and I can definitely see that you have a major problem. Unfortunately it doesn't take much of a grade to create one.

My recommendation would be to widen the bottom of your driveway out to the brick wall and approach your drive way on that oblique angle as opposed to pulling straight up. That should give you more ground clearance with your left wheels up on the high side. Backing it up that way will be trickier though.

Brian
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Old 03-29-2014, 09:03 PM   #8
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Try backing into the driveway, that way the hitch is elevated a little. Have someone watch the clearance as you slowly back up. You can also lay some wood planks at the drive way entrance & close to the rear wheel so that the wheel can climb on the wood thereby raising the hitch clearance.
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Old 03-30-2014, 06:13 AM   #9
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Quote:
Originally Posted by Boxster1971 View Post
Approach angle (alpha) = 18 degrees
Departure angle (beta) = 12 degrees
The 12° figure disagrees with the press release that I saw, but I trust that number better; as an engineer, I trust design drawings. So forget the 22° figure I quoted. And thanks to Boxster1971 for the correction!
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Old 04-01-2014, 07:25 PM   #10
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My issue is not the hitch. I scrape the exhaust below the generator. I back down my driveway as slowly as possible and sometimes make it as I break to the street and sometimes don't.
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Old 04-01-2014, 07:33 PM   #11
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My issue is not the hitch. I scrape the exhaust below the generator. I back down my driveway as slowly as possible and sometimes make it as I break to the street and sometimes don't.
That is odd. The generator exhaust on mine is up and out of the way, except for the very tip right behind the left rear wheelwell. If I scraped my generator exhaust, I'd be scraping the propane fill port on the other side as well.
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Old 04-01-2014, 08:11 PM   #12
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Quote:
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My issue is not the hitch. I scrape the exhaust below the generator. I back down my driveway as slowly as possible and sometimes make it as I break to the street and sometimes don't.
Sounds like you street gutter is taller than mine.

Can you go into the street at an angle?
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Old 04-01-2014, 08:13 PM   #13
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My 2008 Sprinter 2010 Airstream has the exhaust as the lowest point. I wonder if mine was re-engineered. I have never seen it on a lift, but I would like to route it differently.

Anyone else have a 2010 with the same generator exhaust?
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