16" vs. 16.5"

[k5blazinredneck]

I bought a set of rims the other day thinking that they were 16". But now I'm not so sure... The guy that i bought them from swears that they are 16". But when i picked them up, they had 16.5" military tires mounted on them. I cleaned them up and there is no stamping on them stating the size? I have had many shops measure them and they all say that they dont want to call it because they dont want to be wrong. Is there any way to check what size they are? I have tried just a tape measure and from bead to bead they measure around 15 3/4"? I think they are the Pacer Chrome modular wheels. That is what they look like, but im not sure if they are made by another brand. The only stamping on the backside of the rims are "GM" "5-92"(date made im guessing?) Any help would be greatly appreciated!! gotta buy tires soon and i dont know what size to buy.

 

[NorCal_Chris]

this is what the inside of a 16.5 looks like. Smooth slope to edge of wheel, no flat spot with a lip to sit tire on like a regular wheel.

 

[Fordum]

Odds are if they had 16.5 on them, that is what they are. I suspect you might get the bead to seal with 16.5s on 16s, but the other way is dangerous.

The most obvious difference is the shape of the bead flange on the rim. Whole number rims are squared off, while half sizes are more sloped.

That is why I hate my 16.5s. Not only will the bead break before the tire goes completely flat sometimes, but I have had the tire rotate on the rim while fully inflated without losing air.
Just will not stay balanced, since the weight stays at the same place on the rim while the tire moves.

 

[chulisohombre]

16" has a 90 degree safety bead while 16.5 has a 45 degree non safety bead. I'd say rim is what the tire was on there as well.