I'm not that great with it unless I'm in front with a tape measure and will try to explain it best as I'm able but don't take my word as gospel, check it all out for yourself. Many articles all over the forum and web to verify or negate what I'm about to say.
The entire wheel diameter is the rim size plus the top and bottom of the tire.
I was running the stock 16" rims on my 02 with factory ride height. My tires were 275/70/16. The height of my entire wheel was 31.3.
I changed rims and tires going to 18" rims with a tire of 275/65/18.
The height of these tires was just under and inch taller despite the shorter sidewall because the rim was taller.
The offset of the factory rim was 24 or 28 on the positive side so the tire sat well inside the fender.
With the larger rim it's offset as 14 which brought the tire just a tad out if the fender. Maybe 1/4" or less.
Less or negative offset means your tire moved outward on the vehicle. This allows for those deep dish rims that look so cool. The downside is that a larger diameter and width tire has a different scrub radius.
If you take a tire and turn it from center to either direction, the radius it makes is called the scrub radius. This radius isn't perfectly flat or straight. This is because the tire is being angled slightly as it turns.
The trucks scrub radius is daily good considering I went from my stick setup to a larger wheel diameter and wider rims with a mild offset.
I know I have the height clearance to fit 33's under the truck but believe they'd have too wide of a scrub radius with that offset without cutting my plastic.
That's the best I got.. hope it helps some but seriously read about this on Google. That's how I made my swap without making a mistake and having to cut anything.