Why are these tires incompatible?

I've got a base model 2003 Tacoma reg. cab (310k miles) and I've always bought tires at Costco. The OEM size is 205/70R15 but they've always listed 215/70R15 as an alternative and that's what I have run since my first tire replacement. Now they list no compatible tires for the truck, and when I look up by size the tires that come up say incompatible with my truck.
My question is, as long as I match the tire size that's on the truck they should fit, right? I can't figure out why they now say that size won't work.

 

Generally, yes, the same size should work.
If your changing from one All Terrain tire to another (say, different brand) A/T tire, there may be some slight differece in the depth of the tread.

 

Costco probably ran a site update and the new software simply dropped that tire size. Might have just been a glitch on their end. One of my cars used to never show up a compatible tire size. Then all of a sudden it now does. Just depends on the library they are referencing in the software

 

Costco has strict rules, no flexibility.

 

They are scared of people ordering tires that don't fit. So now you have to stay stock sizing. Also lawsuits..
I suggest going in and talking to the shop guys, they are usually much better than dealing with the website software.

I've been able to orders many +1 +0 +2 tire sizes from them. It helps if you have the wheels off and put them on yourself.

 

Costco is notorious for only allowing the OEM size. Maybe try another store. Many members on this forum (myself included) have had good experiences with discount tire.

 

I ordered 265/70/17's for my truck and the guy at Costco Tire Center didn't want to fit it.

I told him to look on their system, I fitted exactly the same size to my previous 2008 Tacoma.

He tried to say it's a different model Tacoma and it would rub but I stuck to my guns

I had to sign a waiver that I can't return the tires if I'm not happy

Their limit is 3% over the standard size

 

I 'conned' my Costo manager to put my 235s on to replace my 215s. Promised him no rubbing.

Now he says that the tires are on and working fine he can replace it with like size.