Hitchlock Pads

Hard to say.  Our van was new in 2008, I discovered after a couple of years that one of the pads was cracked so replaced them then.  Distance travelled was about 6000 miles at that point.

The new pads were then in use till this year so a further  30000 miles and 7 years.

It's how long is a piece of string. Had a new caravan in 2014 with a Winterhoff hitch and in 2016 whilst in Slovenia they wore out, along with creaking, groaning and screeching from metal to metal contact. Just before my trip it had its annual service at the dealer and really wished they had picked it up.

Probably covered about 4,000 miles at that point, but have had them last much longer.

Is this question actually about stabiliser pads rather than a security device.

The rate of wear of stabiliser pads is possibly more affected by the condition of the towball(s) with which it is used than mileage. Long trips on fairly straight roads will produce little wear, whereas meeting up with new deposits of tow ball rust on a frequent basis could be doing more damage.

2000 miles does not seem long.  However, easy to check the wear yourself.  On an ALKO lock; hitch up to car and push lever down.  Pressure should be felt between the marks on the lever.   

The tow bar ball has no rust as it is the detachable type and is stored in a bag in the car boot. The lever has always needed a firm push to lock it in position. There has been no creaking sounds. 

Al Ko estimates the lifespan of the pads to be 33000` (google -  ALKO friction pads lifespan) highly unlikely they would wear out as such after 2000` unless they were damaged by contamination of some sort.

Very easy to maintain, clean and replace if necessary yourself, there are full details on Alko's website, you can take the side pads out in less than a few minutes to give them a clean, it is carbon build up from your cars exhaust that causes the problem, a quick rub with very fine emery paper then a spray with brake and clutch cleaner gets them back as good as new and squeak free..I'm sure they should do more than 2000 miles, I've never replaced mine and I must have done well in excess of 25000. 

Our dealer always gives us any old parts they have replaced so that I can see the wear. I don't have to ask.It seems to be their policy.