I've had my wrangler for a week, and am putting on my Tflex BB tomorrow, so I'm in the market for new tires. I'm trying to decide between 33" and 35" (as well as sizes in-between), but i'm a little confused with something, so confused that I'm not sure exactly how to put the quesiton.

Basically, why are there two ways to state tire sizes, 305/70/17 vs. 33x12.5x17 for example. Why two different methods to state height and width??

Also, what's the relationship between backspacing, tire width, etc. I have a Rubicon with stock rims/tires. Everyone says the 2.5 BB will fit 35", I'm not sure if I'm going to go that big, but am I right in assuming that any 33" or 34.5" (that's that some of them measure) will fit?

I guess what i'm looking for is "tires 101". Thanks for the time!!

-chris

 

This may help with the tire size questions.

http://www.miata.net/garage/tirecalc.html

The 305/70/17 is a metric measurement the 33x12.5x17 is a standard American measurement.

 

305 mm wide, and 70% of 305(213mm) is how far it comes off of the rim of whatever size wheel you have

 

let me see if i can narrow down my question

glwood6 has a rubicon 2-door, and he installed the BB 2.5" lift, and put on Cooper STT's, which look real nice. He chose 33x12.5x17.

He said he considered 285/70/17, which by my calculations add up to 32.70" tall. But he went with the 33x12 because they were wider.

1-they are wider b/c 12.5 is greater than the width of the 285's, right? (285mm / 25.4 = 11.22???????

 

here's his post

Wheels are 8.5", approximately 4.75" backspacing.

I considered 285/70R17 BFG MT's, but comparing them to the Coopers, they probably would have not been any taller than these mounted on the same rims, since they are narrower. Pulling the sidewalls out to 8.5" would have taken a little away from the overall height. I decided to keep these tires with the extra width, even though they are only about 1/2" taller than stock BFG MTs after mounting...I was hoping for a little more height, but am happy with this for now. No speedo adjustment necessary, and fuel mileage will only be affected by a little more friction due to wider footprint...I can live with that...

glwood

https://www.jk-forum.com/forums/show...light=teraflex

 

Yes, that's correct.

 

ok, so what do I need to know to make sure that any particular 33" tire I get will not rub. Well, from what i've read i wont have much of a problem with 33's, but what about 35's.

also, isn't my stock wheel 8.5" wide? so a 12.5" wide tire sticks out from the rim 2" on each side of the tire? wow, i didn't realize that tires were that wider than the rims.

 

I'm also new to this whole Jeep thing and mods, but here is the site I used to understand all the diff. tire measurements:

.tirerack.com/tires/tiretech/techpage.jsp?techid=46