285/70 r17 tire size difference between brands?

Has anyone noticed a difference in tire sizes between brands or rated loads of the same tire specs? I kid you not a buddy of mine parks next to me at work and he bought 285/70 r17s because I had them on my tacoma. We both have 3rd gen tacos. I bought nitto ridge grapplers and he got falken wildpeak at3s. When parked next to each other, we both definitely agreed his tires look they have atleast an extra inch of diameter even though we both have 285s/70 r17s and both are C rated.

 

Reading the manuf website will give you their dimensions along with lots of other data.

Yes sizes are not standardized. But an inch does seem a bit much.

 

There are SLIGHT differences. In most cases the basic tire is the same, but some have more tread than others which makes the overall diameter slightly different. E rated tires are a tiny bit larger in diameter.

Wider rims stretch out the sidewalls and will reduce diameter more than thinner rims.

More air pressure will slightly increase diameter.

New tires will be about 1" larger in diameter than the same tire with 40,000 miles on it.

The 1st 3 digits tell you the width of the tire at the sidewall. But there is no industry standard for the width of the tread touching the ground. You just have to look it up on manufacturers websites. A tire with a wider tread width gives the illusion that it is shorter than it really is compared to a tire with a narrow tread width.

I suspect that a combination of all of the above is what you're seeing.