FSM Front brake pads size 16inch vs 17inch?

I just going through the procedure for doing my front brakes on MY2017 Limited 2.4i H4. I came across a spec in the factory service manual that I'm a bit confused by.

There's a 16 inch type and a 17 inch type brake pad listed in the FSM. Linked here: https://imgur.com/a/ckyUMbM

I'm not sure how to tell which would apply to my car. Does the size refer to the rotor size?

Prior to MY 2015, I believe that standard equipment for Legacy (and Outback) in base trim was 16-inch steel wheels. The Subaru parts catalog only lists one choice of pads for a 2017 Legacy Limited 2.5:

Front: 26296AL03A

Rear: 26696AL01A

I'm pretty sure you're right about the wheel size. However, I do not believe they are referring to wheel size. The FSM is titled 2017 Outback/Legacy Service manual. I am a bit doubtful they would include information from a prior generation in this manual. In addition, I found a couple blow-up diagrams of both 16 inch and 17 inch types of brakes. There is a small difference in their parts and a difference in their torque specs for the caliper bolts, caliper bracket bolts. Check part number 18 and 15 in the 16 inch diagram. They do not exist in the 17 inch diagram. I'm curious to know what you think. Images are linked below.

https://imgur.com/a/e94yrDy

There's a 16 inch type and a 17 inch type brake pad listed in the FSM ... I'm not sure how to tell which would apply to my car.

I'm curious to know what you think.

I've always been curious about the two different front brake variants myself, but I haven't been sufficiently motivated to do the research until now. The references I used are the 2015 Legacy/Outback FSM, the glossy 2015 Legacy sales brochure, and the glossy 2015 Outback sales brochure.

The key difference appears to be the diameter (and thickness) of the front disc rotors:

2015 FSM: front, "16-inch": 11.57 inch (294 mm) OD x 1.10 inch (28 mm) thick

2015 FSM: front, "17-inch": 12.44 inch (316 mm) OD x 1.18 inch (30 mm) thick

2015 FSM: rear (all): 11.81 inch (300 mm) OD x 0.67 inch (17 mm) thick

2015 Legacy Sales Brochure: front, 2.5 engine: 11.6 inch OD

2015 Legacy Sales Brochure: front, 3.6 engine: 12.4 inch OD

2015 Legacy Sales Brochure: rear (all): 11.8 inch OD

2015 Outback Sales Brochure: front (all): 12.4 inch OD

2015 Outback Sales Brochure: rear (all): 11.8 inch OD

So ... (at least for Legacy) 2.5 engine => "16-inch" front brakes, and 3.6 engine => "17-inch" front brakes. As further confirmation, a Subaru training document (MSA5P1926C, June 2014) indicates that all 2015 Outbacks (2.5 or 3.6) have the "17-inch" front brakes and that only 2.5 Legacys have the "16-inch" front brakes. (See attachment.) This actually makes sense, since both the Outbacks and the 3.6 Legacys are heavier, and the 3.6s also have a more forward weight bias.

It's worth noting that some details of the front brakes appear to have changed at MY 2017 (i.e. MY 2015-2016 vs. MY 2017-2019), but I didn't pursue that since I don't have access to the relevant Subaru documents.

So far I have found no authoritative answer to the question of where the "16-inch" and "17-inch" designations originated, but I still tend to think they are somehow related to minimum compatible wheel size (for caliper clearance).