255/55R19 would be just about the same overall size as 265/50R19.
265/50R19 vs 255/55R19 calc
Most tires I've seen in the 255/55 are XL, have a 111 load index and V rated or higher, whereas the 265/50R19 is 110V from what I've seen; you ideally don't want to go a lower load index than what came stock, but it's ok to go to a higher load index.
The 255/55R19 also seem to be a bit less expensive than the 265/50R19. The tire would fit on an 19x8.5 wheel so you should have no issues as far as fitment is concerned even though the 255/55 tire is a wee bit taller than the 265/50 (and actually this will probably give you a better ride with more sidewall to cushion).
And if you're looking online for the tires, valuetread.com has the Nitto NT421Q which I would recommend over the Toyo tires, and at $160 ea in the 255/55R19 (Shipping is roughtly $26 per tire at this place):
Nitto NT421Q in 255/55R19 at valuetread $160
Nitto NT421Q in 265/50R19 $217
Check to see what your local Discount Tire can do for you; generally they are pretty good at matching or beating prices after freight for online vendors.
255/55R19 in the Chicago area at DT (I just took a guess at your area in IL) at the same price point of $195 of those Toyos on treaddepot.com, I'd think about the Bridgestone Dueler H/L Alenza Plus which I'd likely pick over the NT421Q tires, but it'd depend on what kind of driving I'd be doing.
