[ruturaj001]

Originally Posted by Luns

My 2017 '86 has no foam spacer under the tire. Toyota's owners manuals seem to bear this out; the later versions that cover TRD edition, they show the foam spacer only for cars that have a 17" spare wheel, while 16" spares do not have it. I haven't checked Subaru's equivalents, but expect they would be the same.

The parts diagrams I see for this part number seem to indicate it's a sheet metal 'volcano' that's spot-welded into the bottom of the spare tire well to provide the nut the retain bolt threads into. Presumably they wanted this nut higher to allow a shorter bolt for more accurate positioning. It's shown on the same figure as other sheet metal components forming the trunk compartment.

The need for the spacer isn't so much for the respective tires being 16" and 17", but rather that the 17" rim for Brembo brakes is domed out much more to clear the brakes. So with the tire (rubber) resting on the trunk floor, the centre of the Brembo spare wheel would have to poke through the floor while the regular spare doesn't. The spacer is to bring everything up with the Brembo spare.

Odd observation: between the 16" and 17" spare wheels, the 16" is a closer match to stock 17" tires' effective diameter. The 17" spare wheel is the closer match to the stock 16" (JDM, Australian, China, maybe other makets) tires.

Additionally, the 17" spare from other Subaru models might not necessarily work. I'm thinking specifically of the spare for Brembo-equipped WRXes; some people assume since the WRX has Brembo calipers, the spare must work for BRZs with Brembos too. However, what they're missing is that the instructions for the WRX are to put the spare wheel on the rear, and install the fuse that puts the car into FWD mode. I imagine its the same story with other AWD Subarus.

So unless somebody has a way to put their BRZ into FWD mode, I wouldn't simply conclude some other Subaru wheel works. It might anyway, it might not, but you really need to test fit to know for certain, and not just deduce that it does.

Thanks, I was pretty sure I would get PP installed or upgrade to car with PP sometime down the line, I didn't put that much effort in to writing and researching 16" wheels.