Tires: mounting 22 tires on a 22.5 wheels, tire placard, rim diameter

Question
Hi,

I currently have 22.5" wheels/tires on my dually pickup & was wondering if 22" tires will fit on the 22.5" wheels. I'm looking to do so because of the larger variety of tires availible in 22" & the 16 ply rated 22.5" tires have a rough ride & are faily heavy. Please let me know what you think...Thank you.

Answer
Jason,

DO NOT - repeat - DO NOT mount 22" tires on 22.5" rims.  The rim diameter is the rim diameter and trying to mount tires on wrong diameter rims can cause the tire to explode!  People have been killed in the process!!!

But you have a bigger problem than that - so let's start at the basics.

On every vehicle sold in the US, there is a sticker – commonly called the tire placard - that lists the original tire size and the proper pressure for that size.  The placard is usually located on a doorpost or in the glove box – but sometimes it is located in the trunk or on the fuel filler door.

So what does that placard say was the original tire size and the proper pressure for that size?