I know litter tracking annoys a lot of people so I thought I'd share this...
Recently I was doing to get rid of an old bath mat, one of the more old- fashioned in style which is made up of lots of little loops of fabric. As I'd just moved our litter tray to a new area and I was going to get rid of it anyway I thought I'd cut the mat to size and use it underneath and in front of the tray to protect the carpet from any overflow.
And to my surprise it works like a dream for litter tracking! I still get the odd bit she kicks right out of the box, but when I came to Hoover it the first time I realised that it was full of litter - those little loops of fabric work really well in getting it off her feet.
All I need to do now is buy one in a decent a colour as the existing one is bright yellow and clashes with everything else in the house...