the only authorized pirelli delaer in all of PK is in blue area (soon to move to F-8 behind ali medical centre) and tyre prices are down to the size. you can call omer shakeel on 051-2279249.
as for yokohama, there is no OFFICIAL dealer in PK as yet.
Goodyear is represented in LHR as bobby already mentioned. their number is 0427351049 and their ISB rep's number is 0512278447.