My son has MK 11 escort with 6.5j rims, what size tyres should he get.

check out the tyre guide on polleysports web site. tells which rim widths each tyre will fit, i am using 205/60/13 on all 4 corners but my wheels are 6" front and 8" rear. this tyre will fit both rim widths

1 ran 185 70 13's on my mark 2 back in the day. They are renown for skipping when cornering so be cautious of dropping the profile too much

i'd say 185/60/13 on the front for sure, with either the same on the rear or 205/60/13 if you fancy wider tyres on the rear.

I run 6x13 wheels on my Escort with 185/60.