Wheel measurements

CybrSlydr

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So, what I'm familiar with when it comes to tire sizes is apparently quite different than you folks.

For example, my M3 has 18" wheels - 225/45R18 in the front and 255/40R18 in the rear.

Now, I look at the wheels/tires on what you folks are driving and you're talking about 31s, 33s, 35s, etc. Obviously this isn't the rim size, which is what I'm used to. I assume this is the radius of the tire?
 
So, what I'm familiar with when it comes to tire sizes is apparently quite different than you folks.

For example, my M3 has 18" wheels - 225/45R18 in the front and 255/40R18 in the rear.

Now, I look at the wheels/tires on what you folks are driving and you're talking about 31s, 33s, 35s, etc. Obviously this isn't the rim size, which is what I'm used to. I assume this is the radius of the tire?
They are talking in plain terms. You can “usually” assume when someone is talking about 35s (35x12.5r15), 33s (33x12.5r15/33x10.5r15) ect. You will find users on here running a metric size tire usually run a 16” rim. Most people running a 15” rim get quite a few more tire choices.
 
...or a 285/75R16 which come out close to what we'd refer to as a 33x11.25R16. (That's not a real tire size) There's several good tire size converters on the Web that will make translating much smoother and easier. Most, if not all, tire that are called out as a diameter and width, like 31x10.50, are LT or light truck tire sizes. It's a left over from the bad old days.
 
31x10.50 R15 is a 31" diameter tire with a 10.5" section width on a 15" diameter wheel.

A 225/45 R18 is a 255mm section width with a sidewall height that is 45% of the section width on a 18" diameter wheel.

"R" is for radial. Letters like S, H, V, M are speed ratings.

Makes perfect sense, right :D
 
31x10.50 R15 is a 31" diameter tire with a 10.5" section width on a 15" diameter wheel.

A 225/45 R18 is a 255mm section width with a sidewall height that is 45% of the section width on a 18" diameter wheel.

"R" is for radial. Letters like S, H, V, M are speed ratings.

Makes perfect sense, right :D

lol Yeah - problem was I'm going from a vehicle where actual tire size (31, 33, 35, etc) is irrelevant and what you use to talk about it is the rim size (yeah, I got 18's on mine, yo... slammed on 19s is dope, etc).

Like switching from Imperial to Metric. :D
 
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LT is light truck. "C", "D", "E" are tire ply ratings. A "C" tire is a 6 ply, "D" 8 ply, "E" 10 ply. Most 16", 17"Jeep metric tire sizes are either "D" or "E" load tires. An "E" load tire has a stiffer side wall and can cause a rougher ride as a result cause our jeeps are light for that load tire, so you'll often see folks recommend a 15" wheel with a "C" load tire.
 
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Wheel tire sizes don't make any damn sense with TJs. 15" wheels get you tons of 31", 32", 33" and other standard sizes. While 16" and 17" wheels get you metric sizes. I can't make sense out of why it is the way it is, but that's just how it is.

For what it's worth, this metric tire converter is a very useful tool in my experience:
https://tiresize.com/metric-tire-conversion/
 
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lol Yeah - problem was I'm going from a vehicle where actual tire size (31, 33, 35, etc) is irrelevant and what you use to talk about it is the rim size (yeah, I got 18's on mine, yo... slammed on 19s is dope, etc).

Like switching from Imperial to Metric. :D

If you brought over our jeep logic to your Beamer lingo, then you'd be slamming on 255's brah!
 
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LT is light truck. "C", "D", "E" are tire ply ratings. A "C" tire is a 6 ply, "D" 8 ply, "E" 10 ply. Most 16", 17"Jeep metric tire sizes are either "D" or "E" load tires. An "E" load tire has a stiffer side wall and can cause a rougher ride as a result cause our jeeps are light for that load tire, so you'll often see folks recommend a 15" wheel with a "C" load tire.
Just a little more reading material for ya :D