Reviving this thread. Does anyone happen to know? I measured and seems like the diameter is 55mm or ~2.25". Could anyone confirm with a part number?
I have found 54 mm mentioned everywhere. But the next size is 63 mm as best of my knowledge, something close to 54 will be OK. It’s quite standard.
As far as I know, the Toyota part number, for all 3rd gen riims, is: 42603-52110 Besides the bore diameter, the dimension/location of the internal groove in the bore drives the dimensions of the locking tabs. FWIW, the location of this groove apparently shifted in gen 4. I purchased some EBay caps, purportedly "genuine Toyota". They were in fact knock-offs. I was able to get them to work, but only after some testing/comparing (to genuine caps that came with our 17" rims). The knock-off caps had a variation in the bevels just under the front face of the caps, which caused them to not seat properly, and also prevented the locking jaws from engaging in the groove. An hour of patient work with a dremel resolved the problem. Moral of the story I guess, either go with genuine, or be prepared for some run-around.
