It's the ID that's the important bit I guess, if that's a snug fit so long as the OD is inside the housing it'll be ok. I measured the rear ​housing at a hair under 27mm, front at 22.5mm.
Setting you up for a gag, but my rear washers are ok, it's the front that are knackered. If I was doing it myself I wouldn't bother with the rear.
It's the ID that's the important bit I guess, if that's a snug fit so long as the OD is inside the housing it'll be ok. I measured the rear ​housing at a hair under 27mm, front at 22.5mm.
Setting you up for a gag, but my rear washers are ok, it's the front that are knackered. If I was doing it myself I wouldn't bother with the rear.