Wheels measure 21" - listed as 20" alloys on specs

[G00S]

I was looking at tire options on tire rack and now I feel like I'm going crazy here or something but I measured my wheels and they measure 21 inches in diameter. My tires are 265/60R20 though suggesting a 20 inch rim so how does this work? Also on the paperwork I got it lists 20" wheel upgrade. Posted a picture of my wheels and tires.

 

[abt]

You are not crazy, something must be wrong. To ease your mind, those wheel diameter numbers are confirmed by the tire size, which both of them were probably measured (and cross referenced) a million times.

 

[Mopac51]

Tire size is measured from bead seat to bead seat, which is lower than the outermost 'rim' portion. Size comes from where the tire actually makes air-tight contact, not from what you see on the outside

 

[ovʀʟxnᴅ]

This. It's not that you're measuring wrong, just from the wrong place for the measurement you're after.

 

[G00S]

Tire size is measured from bead seat to bead seat, which is lower than the outermost 'rim' portion. Size comes from where the tire actually makes air-tight contact, not from what you see on the outside

Thanks that makes sense.