Long car ramps

Both wheels are driven, but length of carpet attached to the ramp is what you want.

Put them on a surface that doesn't allow them to be pushed so readily, or loop a strip of material such as carpet around the bottom rung, so it can't be pushed forward.

Or use a front wheel drive car.

Rawl-bolt them to the drive when needed?

In message , Mr Sandman writes

Many years ago, I made a pair of extenders, using hardboard - thin ply would do. Cut a length of board same width as the ramp and twelve+ inches long. On to one end, nail or screw a length of 2 x 1, then hook the 2 x 1 under the end of the ramp. The weight of the approaching wheel prevents the ramp moving forward.

I find a couple of concrete blocks placed on the ground at the far end of each ramp provide enough friction to get you going. Or a bit of 4x2 timber to keep both ramps lined up, and get someone to hold it down with a foot as you start climbing.

(I've never got round to using carpet as described elsewhere).

carpet is very cheap, very lightweight and easy to store, plus needs no extra assistance, big lumps of blocks or wood plus someone willing to stand in front of a moving vehicle are not.