My tire switching nightmare

My two 2008 Prius taxi's came with 195/55/16 Bridgestone Turanzas. They were shot at 45,000 km. When I looked around for other tires in the same size there was a very limited selection.
Having checked Consumersreports I knew the Mich x radial had pretty good tread wear. When I went to Costco they said they did not have the x radial in my size and that I had to stick to the "v" rated tire. I told them that my experience with the Turanza "v" rated tire was not good.
I went to the Toyota dealership to talk to whoever might help me with info on my choices. The guys at the parts counter pointed out that the 185'65/15's were the same circumference and that the selection of tires in that size was pretty good.
I went back to Costco to see if they had the x-radial in the 185/65/15 size.
They said they did but couldn't put them on my car unless I had a letter from Toyota saying it was ok because the car came with 16 inch rims.. (little did I know that on their site the x-radial in the 185/65/15 shows up as a match for the 2008 Toyota)
I went back to the dealership and they told me to phone Toyota Canada.
While I was talking to someone at Toyota Canada he pointed out that on page 470 of my manual it had both 195/55/16 and 185/65/15 listed for tire size. They told me to take the manual to Costco and that should be all I need. At that time I felt it was safe to by 8 15 inch rims.
The next morning I got to Costco 1/2 hour before they opened (they have a first come first serve policy). I showed the manual to the same guy I had talked to the day before. He said they still couldn't do it without a letter.
I asked why not when the manual said 185/65/15 was a match. He told me that the manual was a "generic" manual. By this time I am starting to get a little pissed.
I phoned Toyota Canada about getting a letter and they said they didn't do that and I would have to go to my local dealership for a letter.
I phoned the manger at the dealership and he said he wouldn't do a letter because their policy was the cars are to stay with the size of tire they come with. Now I am starting to really get pissed.
I went back to Costco and fortunately was able to talk to different "tire expert".(one with a brain and listening skills) He said that all they could do for me at that point was mount the tires on the rims and I would have to take them somewhere else to have them put on the car and that meant the extra cost of $40 per car to have them switched and have the old tires disposed of.
He did say that the boss was on a holiday and if I waited a few days he thought he would try to get permission to switch them and do the whole job. I didn't want to wait through the weekend as the tires were so worn i didn't trust them to hold up with my cars going 24 hours a day over the weekend.
After the first car was done on Thursday The taxi commissioner ran it around the track and the meter was bang on and no calibration was needed. When I took the second car in on Friday I pointed that out to the tire guy with the listening skills that it worked perfectly at the track which meant the circumference was the same and to put that in his e-mail to the boss.
Saturday I received a call from him and he said that in the future I could put the 185/65/15's on with no hassle.I thanked him and told him that I had had enough hassle from them to last me 10 years.
What I have a hard time with is why when the manual says 185/65/15 is a match Costco wouldn't make the switch and Toyota wouldn't issue me a letter saying it was ok.
At least they are on now and I should only have to change the tires twice a year (x-ice for the winter and x-radial for the other 7-8 months) instead of 3 times times a year like it would have been with the Turanza's.
I had a badly needed relaxing weekend at the cottage after all that bs.,

 

SKTN--- I had 15 inch rims for them to put the tires on. The cheaper price on a 15 inch tire and the x-radial having good tread wear made it worth the effort. I put 140,000 km a year on the car and spend a lot on tires.

 

When I contacted Toyota about a letter they said that page 470 in the manual should do the trick. Apparently Costco doesn't believe the info on page 470. Why? I don't know. I will be firing off an e-mail to Costco to try to find out why. I will also fire off an e-mail to Toyota to find out when the manual says that both the 195/55/16 and the 185/65/15 are a good match,
why they would not issue a letter to say that the 185/65/15 was ok on the car.