Hi keith
Try 3M, they do 3 types of reflective yellow for traffic signage.
Class 1 High Intencity= for A road directional signage
Class 2 Scotchlite= for tempory/diversion signage
V.I.P. Diamond grade= for emergency vehicles
I would recomend the class 2 Scotchlite very similar to avery reflective
but can be a pain to remove 👿 . some councils have red class 2 on there vehicles as markings.
Also you must check if you are allowed to use yellow for vehicle markings
as there are regs about this (!)
Hope this helps
C W C