General interest: comparing serpentine belt part numbers

This is a non-essential "nerd out" thread about the subtle differences between two identical part numbers from the same OEM, manufactured in different locations. No particular take-away or signifcance intended.

The part in question is the 2nd gen / 1GR-FE V6 4.0L serpentine belt, AKA Toyota part #

$60 90916-A2001 Alternator and Fan Belt

90916-A2001. I ordered two versions of this belt, one from a Toyota dealership, the other on Amazon as a plain BANDO part #7PK2120. The Toyota version is made in the USA, and also marked "

$20 BANDO 7PK2120 OEM Quality Serpentine Belt

BANDO 7PK2120" on the belt itself, so nominally these are the same part. The BANDO-branded version is made in Japan.

Dimensionally-speaking, in all dimensions (length, width, thickness, number & profile of V grooves,) these belts appear interchangeable. Both are made of EPDM, though the Japanese-made belt "feels & looks higher-quality." Both would no doubt fit properly on the serpentine pulleys and wheels with about the same tension.

The main difference between them is the surface roughness of the outside of the belt. I wonder why, for the exact same part number, the Japanese-made belt is very smooth on outside, while the other (the USA-manufactured, Toyota-branded part) has a distinct grid-pattern roughness to it. The Japanese-made version is also about 4.5% heavier than the Toyota-brand / USA-made one.

When I do the serpentine belt on my Taco I'm going to use the Toyota-branded one just in case the outside surface texture makes a difference in operation or wear life. Only thing that comes to mind is maybe the Japanese-made smooth-surface version is meant for vehicles that have composite, plastic, or rubber-coated pulleys, instead of metal pulleys.

Belt specs, as measured:
Bando 7PK2120, Japanese-made: 226 grams, ~0.970 inches wide, 0.167 in. thick, +/- 0.005.
Bando 7PK2120, USA-made: 216 grams, ~0.990 inches wide, 0.171 in. thick, +/- 0.005.

Photos follow. In all side by-sides, the Japanese-made version is on the left, USA-made on the right:

 

I have the Bando Belt as shown in your pictures, my belt is the same as yours on the left (Japan in your picture), but mine is made in the U.S.A.

Doesn't have the textured surface.

I also have a Michelin P#

$38 SMAMV7PK2120 MICHELIN Serpentine Drive Belt SMAMV7PK2120

SMAMV7PK2120 that I may use instead of the BANDO.

I've had the belt for a few years as my carry spare I was traveling a lot back then so mfg. could have moved out of country.

Thanks for your post.

TOMB