Slippers for me, wears out socks too quickly otherwise. When years ago I made the switch to leaving boots on the step outside I was amazed how much cleaner the lorry was inside without the dust and grime being brought in.
My boots/trainers live by the side of my seat as soon as I get in the cab, I actually take them off as I’m getting in so they never go anywhere near my floor. I drive in slippers, which I usually kick off as I’m on cruise and have I shift, so don’t use the pedals much at all.
I started taking my boots off when I was driving a tipper full of guts and snot, the abbatoirs and rendering plants have stuff on the floor you definitely do not want in the cab with you as rotting flesh tends to whiff a bit.
Now it’s just a habit, which as Switch has said, helps to keep the cab clean, I tend to go in a lot of muddy yards and I have a flat floor, so anything on my pedals/floor mat will eventually find its way into my bunk and I don’t want that.
I Wear euroroutier Clacks slip on, They are classed as safety wear as they have steel toe caps, and a strap round the back really comfy
Slip on trainers while driving for me, work boots for when I’m outside the cab and working.
Shoshaye:
Boots on the step and I drive in slippers.
Me also, get ribbed by some of our drivers for doing so but take a look in their cab and I wouldnt let my dog in some of them. 
boots off for me, I don’t wear my shoes in my house at weekends so why should I wear them in my house for the week, got a good quality pair of flip flops for in the cab.
For the lads that drive in socks do you find it hard on the feet if you have press harder on the brake?
Reef:
Safety boots left on step
I’ve always wondered about this when I’ve seen it mentioned… so have to ask: don’t they fall off? 
Noooo,you wedge them in with the milk carton 
…the top two steps on most wagons I’ve driven the door closes over them,only the bottom step is exposed.
ShropsBri:
For the lads that drive in socks do you find it hard on the feet if you have press harder on the brake?
Can’t honestly say I’ve noticed it being hard on my feet Bri. I would say though that if I had to press the pedal hard enough to hurt my bare feet then I’m about to enter a world of hurt where my delicate tootsies would be the least of my worries! 
Chris1207:
I’ve always wondered about this when I’ve seen it mentioned… so have to ask: don’t they fall off?
as already mentioned, the door keeps them covered. you’ll be in for some wet loafers if you happen to be driving a scania in rainy weather though takes some gaffer tape to reroute the water away from your shoes.
ShropsBri:
…the top two steps on most wagons I’ve driven the door closes over them,only the bottom step is exposed.
The steps are exposed on an Iveco Ecostralis.
No use on a Magnum either 
milodon:
Chris1207:
I’ve always wondered about this when I’ve seen it mentioned… so have to ask: don’t they fall off?as already mentioned, the door keeps them covered. you’ll be in for some wet loafers if you happen to be driving a scania in rainy weather though
Or as seen here, metal plates made by the apprentices at Scania Biler Vojens, at a modest cost of DKK 135, and they do work.
Reminds me of driving in Italy. Polizia stopped my F12 when my exMrs was driving. When he opened the door he saw she had no shoes on. He said she had to wear shoes and shoes with a heel…so she asked me for her stilettos! A big smile on his face and he let her continue.
By means of a heel he meant a back so they cant slip off, no flip flops. No diecimille lira fine for her! He completely forgot about the speeding fine!
I have always driven barefoot(although illegal), even in winter for multiple reasons - 1)my long lanky 6’ 5" frame and size 13 feet where every millimeter of leg/footroom counts, Renault Magnums are a particular horror. 2)to avoid appalling foot odour/foot diseases in summer especially in Spain and Italy in 40 degree heat. I have been nicked twice in Germany but luckily got away with a verbal warning both times - the police explained that closed shoes(no open heels) must be worn. In summer when you get pulled into a control, the copper races over and rips your door open before you have time to react and exclaims ‘you’re not wearing shoes - 40 euros’. Duh!
I’m all for real health and safety - God forbid we return to the days when Clyde shipyard workers got brain damaged with a glowing hot rivet through the skull and got no compensation, I even quit smoking 3 years ago and wear lime green waistcoat to keep ‘em’ happy. Solution - I keep a pair of slip-on steel-toe Grafters AND a pair of flip-flops by my seat. God bless the Italians, at least they are fair!