Novak Conversions Jeep Wrangler TJ radiator

Still confused on wheel sizing

The problem has to do with how the rim is constructed. Generally, offset is calculated (near as I can tell) by rim width which is the inside dimension that the tire beads butt up against. Offset math generally moves that back and forth but it never exceeds the actual rim width.
View attachment 568883

Backspacing doesn't care about the published rim width.

This is how we all measure backspacing. Note how flat the rim lip is.
View attachment 568884

Then you have a rim like this and if they were the same width, your backspacing number would vary from the above.

Versus this-
View attachment 568885

Versus this-
View attachment 568887

Point being, if we're trying to move from a 3.5" back spaced wheel to something closer to 4" to tighten up our steering with an improved scrub radius, it is probably best to see the wheel in person and do some actual measuring.

BTW- if you swing by my house with a rim and measure it like this, just know you have invited a swift kick to the taint for being a dumbass.

View attachment 568888

The way I've always understood it is that your BS is measured striaght from the WMS to the very rearmost of the bead. like your straightedges for measuring show (excluding the limp ruler :ROFLMAO:). Offset is a measurement of how far off the centerline you are, but to convert it, you're supposed to take the nominal rim width (8" for example), add in 1" (for both beads), and then that gives you the total wheel width to divide in half and find the centerline with.

I've never known wheel construction to play a part, I've always thought you add in a half inch per bead to get the total width, since that is the "standard" (that's been the standard in all the conversion calculators at least).

I think people get misled by leaving off the bead width. For example, on a wheel known as being 15x8, they assume 4" is the centerline, and so 4" BS equal 0 offset...not correct. Have to add in the inch of bead width, centerline becomes 4.5, now a 4" BS wheel is somewhere around -12.5mm offset (offset by half an inch, negatively).

But yes, I do get your point that if the bead is designed differently, then the BS of two different wheels could be different. I would think if it was different enough due to the bead, that the offset would have been different as well, though. Since offset factors in both beads, or is supposed to.
 
  • Like
Reactions: Mike_H
The link posted above to another thread here will give you that information for a number of factory wheel offerings. Follow the link to the thread for the full list. 👍

I keep meaning to reach out to Chris on that thread. There are a few wheels on that listing that need some correction. For example: no 7" stock wheels that I know of have 5.5" BS. They are all 5.25" (31.75mm offset). Similarly, I know the Gambler wheels are 8" wide and have 5.5" BS, not 5.25",
 
  • Like
Reactions: chili_pepper
The way I've always understood it is that your BS is measured striaght from the WMS to the very rearmost of the bead. like your straightedges for measuring show (excluding the limp ruler :ROFLMAO:). Offset is a measurement of how far off the centerline you are, but to convert it, you're supposed to take the nominal rim width (8" for example), add in 1" (for both beads), and then that gives you the total wheel width to divide in half and find the centerline with.

I've never known wheel construction to play a part, I've always thought you add in a half inch per bead to get the total width, since that is the "standard" (that's been the standard in all the conversion calculators at least).

I think people get misled by leaving off the bead width. For example, on a wheel known as being 15x8, they assume 4" is the centerline, and so 4" BS equal 0 offset...not correct. Have to add in the inch of bead width, centerline becomes 4.5, now a 4" BS wheel is somewhere around -12.5mm offset (offset by half an inch, negatively).

But yes, I do get your point that if the bead is designed differently, then the BS of two different wheels could be different. I would think if it was different enough due to the bead, that the offset would have been different as well, though. Since offset factors in both beads, or is supposed to.
I've paid attention to quite a few wheel threads regarding offset and back spacing and this is the first I've seen mention of adding 1" to the wheel width to get the 1/2" per side to calculate where the tire bead sits relative to back spacing.

What I've run into is trying to measure back spacing on lots of rims and noting that some are easy since very little of the tire is in the way and others need an exact length straight edge to sit on the wheel lip.
 
I keep meaning to reach out to Chris on that thread. There are a few wheels on that listing that need some correction. For example: no 7" stock wheels that I know of have 5.5" BS. They are all 5.25" (31.75mm offset). Similarly, I know the Gambler wheels are 8" wide and have 5.5" BS, not 5.25",

Stock wheels suck. I've measured several that were not what they were reported to be.
 
I've paid attention to quite a few wheel threads regarding offset and back spacing and this is the first I've seen mention of adding 1" to the wheel width to get the 1/2" per side to calculate where the tire bead sits relative to back spacing.

What I've run into is trying to measure back spacing on lots of rims and noting that some are easy since very little of the tire is in the way and others need an exact length straight edge to sit on the wheel lip.

How can you tell me you don't read my posts, without telling me you don't read my posts? ;)
 
I've paid attention to quite a few wheel threads regarding offset and back spacing and this is the first I've seen mention of adding 1" to the wheel width to get the 1/2" per side to calculate where the tire bead sits relative to back spacing.

What I've run into is trying to measure back spacing on lots of rims and noting that some are easy since very little of the tire is in the way and others need an exact length straight edge to sit on the wheel lip.

I only know what I've found on the web, but all measurements and calculations I've done have in person panned out based on adding an inch to the nominal for wheel width as per the Internet advice on how to calculate.

Examples of 2 common stock wheels just because:

15x7 (+31.75mm advertised offset cast into the back of the wheel) - known to be 5.25" backspacing
7" + 0.5" + 0.5" = 8" total width for offset calculation
8/2 = 4" centerline
Flange is 31.75mm positively offset from centerline
31.75mm/25.4mm (1") = 1.25"
4" + 1.25" = 5.25" BS

15x8 (25.4mm advertised offset cast into the back of the wheel) - known to be 5.5" backspacing
8" + 0.5" + 0.5" = 9" total width for offset calculation
9/2 = 4.5" centerline
Flange is 25.4mm positively offset from centerline
25.4mm = 1"
4.5" + 1" = 5.5" BS

I dunno, the math always works out for me following that. Not that I do many calculations, most wheels I deal with I just happen to know offhand what the specs are. I don't deal with a lot of wheels.

Stock wheels suck. I've measured several that were not what they were reported to be.

I like them for their styling and under the flare fitment. I haven't had any issues when them not measuring how they were supposed to, but like I said previously, I don't deal with tons of them.

They are not usually ideal for a difficult-trail oriented build, and I get that.
 
just for farts and giggles
would you all tell me WERE/HOW these would sit on the jeep with "STOCK" flares
and LT30x9.50R15 Falcon Wildpeak tires
will the tread stick out? past the flares
and any other helpfull comments or wheel suggestions you could link to

7inch
https://www.extremeterrain.com/american-racing-jeep-wrangler-baja-satin-black-wheel-ar1725765b.html

8inch
https://www.extremeterrain.com/mammoth-boulder-black-15-8-J100620.html

I’m not sure you’re grasping the concepts. This really isn’t that difficult. The stock wheel specs have been listed. Compare to those.

The 7” wheel linked has 3.75” BS. Stock 7” wheels have 5.25” BS. Therefore, they’ll stick out past the stock flares by about 1.5”.

The 8” linked has 3.75” BS, and stock 8” wheels have 5.5” BS, so 1.75” additional stick out.
 
just for farts and giggles
would you all tell me WERE/HOW these would sit on the jeep with "STOCK" flares
and LT30x9.50R15 Falcon Wildpeak tires
will the tread stick out? past the flares
and any other helpfull comments or wheel suggestions you could link to

7inch
https://www.extremeterrain.com/american-racing-jeep-wrangler-baja-satin-black-wheel-ar1725765b.html

8inch
https://www.extremeterrain.com/mammoth-boulder-black-15-8-J100620.html

And if you don't want to do the math yourself, you can use the offset calculator and offset converters on this page (linked in a response yesterday)...

https://tiresize.com/wheel-offset-calculator/

offset_conv.png
 
I’m not sure you’re grasping the concepts. This really isn’t that difficult. The stock wheel specs have been listed. Compare to those.

The 7” wheel linked has 3.75” BS. Stock 7” wheels have 5.25” BS. Therefore, they’ll stick out past the stock flares by about 1.5”.

The 8” linked has 3.75” BS, and stock 8” wheels have 5.5” BS, so 1.75” additional stick out.

THANK YOU
NOW i get it. with your description
and i dont have to bang my head on my desk anymore
 
Found these today surfing on here

and im going with the canyons
https://www.oewheelsllc.com/Jeep-New-Wrangler_3

then sell the ones I have on it :) and recover the cost + some
 
Found these today surfing on here

and im going with the canyons
https://www.oewheelsllc.com/Jeep-New-Wrangler_3

then sell the ones I have on it :) and recover the cost + some

Just to stir the pot, I prefer the oem Ravines over the Canyons. ;)

wheel.jpg
 
Just to stir the pot, I prefer the oem Ravines over the Canyons. ;)

View attachment 569354

You aren't alone. Still maintain this is one of the best looking factory wheels they put on the TJ series (Moab is a close 2nd)...though I may have been brainwashed a bit as it would seem quite a few TJ's that left the factory did so on those wheels.
 
  • Like
Reactions: LONGJP2
Just to stir the pot, I prefer the oem Ravines over the Canyons. ;)

View attachment 569354

I like the Ravines, but for whatever reason, when trying to buy some used, they seem to be in poorer shape than all the other used options, comparatively. Maybe just the paint job? Seems like every one I see has flaked or discolored all over the place and become an eyesore. That is, unless they were really well taken care of, which most seem to have not been.
 
  • Like
Reactions: 2005 wrangler X ?
I do wish offset was mentioned more. I remember seeing every forum growing up say that back spacing only matters and 3.75in was the way to go and that’s all I needed to know. Well I got 10in wide wheels with 3.625in back spacing thinking that was close to the perfect 3.75in.
Now I just moved to New Hampshire with annual inspections with fender laws and I need to get the tire as close to the body as I can with minimal rubbing as possible to run a genright 4in flare and be close enough to have someone pass it since I don’t believe they’re super strict and need sidewall covered as well. I’ve had to go down this path of knowing offset and backspacing to get the idea that a jk “Moab” wheel with a 7.5in width and 2in adapter will put it at 4.25in backspacing but because of the width of the wheel my tires will be almost 3inches closer in than my current 3.6in back spacing wheels.

My old set up with the 10in wide rims vs jk wheels with spacers are less than an inch difference of backspacing but where the tire actually sits is very different.

Now my question is why is backspacing the only thing talked about when it’s the tire that rubs on things, and placement of the tire is affected by wheel width and offset too? How far the tire sits in or out is affected by all of these measurements yet we only focus on one. Because of the focus on one we fail to actually achieve the closest tire to the tub without rubbing which I assume is the intended goal and some things can change that such as outboards or swayloc making it harder without rubbing.

IMG_3061.png


IMG_3062.png
 
Novak Conversions Jeep Wrangler TJ radiator