Ground Clearance is used to describe the maximum height of an obstacle the automobile can driver over without scratching the underneath (Figure below).

Ground Clearance

Another problem with cars is that they may not be able clear a ramp if the ramp has too much inclination with respect to the ground level. The front bumper may collide with the ramp before the front wheels can maintain contact with the ground and the ramp.

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Is there a specific term for this value (theta in the figure above)?

To give a bit of context, the parking lot near where I live has a ramp that constantly scratches the bottom of my car's front bumper, and I am looking for ways to avoid it.

  • Can you reverse up the ramp, or does the rest of the road layout make that impossible? – alephzero Feb 8 at 12:33
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    If you're in the UK & drive any 'regular' car, complain at the council - you can also claim damages. If you drive a Koenigsegg, forget it ;)) – Tetsujin Feb 8 at 18:54

The terms commonly used are arrival and departure angle - mostly with 4*4...

But to deal with your situation then change the arrival angle by adding blocks to lift the car early.

Of course, you could fit adjustable controllable suspension either electric with an air pump (had that on a Volvo) or even hydraulic...

  • A pretty common statistic provided in Car & Driver magazine for off-road vehicles, not too frequently seen for sports cars, although it could be useful information. – fred_dot_u Feb 8 at 8:41
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    @fred_dot_u especially at the high end, most sports cars are so low to the ground that an blanket value of "no" would suffice for almost any ground clearance related stat. – Dan Is Fiddling By Firelight Feb 8 at 16:24
  • A related measurement is "ramp breakover". – CCTO Feb 8 at 16:58
  • The numbers may be small, but surely there must be some conventions on just how low they can be so that the cars remain compatible with the roads and racetracks they are used on. – Peter Green Feb 8 at 22:03
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    @CCTO, basically, "approach angle" is the measure for the front bumper, "breakover angle" is the measure for the undercarriage, and "departure angle" is the measure for the rear bumper. – Mark Feb 9 at 3:33

As Solar Mike said, it's called the arrival angle. However, an alternate solution to your problem might be to approach the ramp at an angle instead of straight on. This lets one wheel start raising up before the lowest section of your bumper touches the ramp. See this video for a demonstration with a speed bump: https://youtu.be/EQFrKWJli_A?t=368

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    This. I moved to a new house, and my front bumper always got scratched up when I reversed out of the driveway. I started turning hard while passing the steep curb and I no longer touch the ground with the bumper at all. – Mirror318 Feb 8 at 23:42

Not really a solution for a daily arrival at a steep driveway, but one that works for 'ugly' speedbumps - though it takes a few tries to get it right.
It's worth the effort if you have a low-clearance vehicle. It also prevents 'headbutting the roof' syndrome. It does, however, work best on longer cars (& not at all on big (Sprinter, Transit) vans, as they don't have the punch in the acceleration & are too long to get the timing right on the suspension dampers).

On approach drop to a low gear, maybe 2nd, far enough before the hump that you can rev-match to 'coasting' not retardation.
At almost the last second, brake, then release (just a tap). This will make the front of the vehicle first dip, then lift.
As it lifts, that's the point you should time to hit the up-slope.

Then, for a speed bump if not a driveway, as soon as the rear wheels reach the top of the hump, tap the accelerator. This will dip the rear axle & get you off the hump much more smoothly, avoiding dunching the bumper in the road as you leave.

(The number of cars I follow over speed bumps who do the exact opposite of this is excruciating… brake into the bump, release the brakes half way over… meh)

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