I just brought my Tom Tom satnav with trucking maps and it’s asking me for vehicle dimensions, I know I can’t put them in yet anyways due to not starting my job until Monday but where do I find the width and length of my truck?
Is it on that silver plate where it tells you the payload Etc ?
Did it not cross your mind that perhaps we would need to know that type of vehicle it is before asking us? 
8ft5in wide
Depends on whether its artic or rigid etc…
I think Ryan is starting on 7.5t before moving on to cat C.
I haven’t driven a 7.5 tonner for ages and without looking at the plate and vehicle height I would only be guessing, so I’ll leave it to people who drive them to answer.
A tape measure is your freind 
+1 on the last, you might look odd and strange to others who might be watching but atleast you will know 
Try the manufacturers websites, they usually have truck specs on them, if its a recent vehicle.
Their websites will only have the dims of the chassis/cab.
I don’t think that actual dims are marked anywhere on the vehicle itself, apart from possibly the height.
Like said above…tape measure!
What about varying lengths and heights of the body? Why would the make & model be relevant? 
7.5t’s at ours are about 8ft wide x 28ft long and the height should be marked in the cab.