I may have mentioned this before but if, like me, you are a 'pretty average' model painter then you will probably have a lot of trouble getting similar-looking tyres on your vehicles. Should the Heroics & Ros order contain nearly 2 dozen Kfz69s or 70s, this is an especially effective cure for '6mil painting brain cave-in' syndrome. I tried using a fine marker pen to colour the windows on my old white metal buildings but the ink dried a very weird black with a not very subtle hint of bronze iridescence.
I forget who put me onto it but WH Smiths do a handy range of something called a Drawing Pen made by Pilot, from £3:00 to £3:49. Its a very resilient kind of fibre-tipped pen (so doesn't go fluffy & splay out) and uses 'pigment ink', whatever that is. In any case, it is waterproof when dry and does not run or bleed when a coating of matt varnish is applied and comes in a bunch of nib sizes. I have the very smallest, size 01, which I am thinking is OK for fine work like inking in windscreens and quarterlights but a larger size might be easier to use on 'big' areas like tyre walls.
I might give the lower surface of tyres a daubing of HU33 for scuffing prevention as the ink layer is very thin.