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Tire Size vs. Hub Height Survey

Serbonze

TJ Neophyte
Supporting Member
Nov 12, 2015
1,810
USA
New Cooper SST Pros
33X12.50 15
24.6 PSI
15 3/8"
Load range C

@jjvw you may want to explore how people are measuring to the center of the hub. It can be precise or it can be an eyeball, and I think with these small differences you may want it to be as precise as possible? I originally held a tape measure up to to my wheel and tried to figure out how to get an accurate measurement from the center of the hub when that center is six inches in from the wheel. I ended up using a level and doing some calculations. Maybe I'm just dumb and couldn't figure out a simple way, but originally eyeballing it with just the tape measure I guessed 16".

I think the following people have run [edit] or commented about Load Range D or E tires in the past. Not sure if they're still running them now.

Serbonze
I've changed over to load range C. I never measured the hub height when I had the Es so I can't provide any useful information besides current data for this discussion. :)
 
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jjvw

jjvw

0-60 in 18 seconds
Supporting Member
Feb 17, 2018
6,654
Colorado, USA
Here is what we have so far. It isn't really enough to see anything yet. I am also unsure how to present the data.
HubHeights.JPG
 
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jjvw

jjvw

0-60 in 18 seconds
Supporting Member
Feb 17, 2018
6,654
Colorado, USA
...

@jjvw you may want to explore how people are measuring to the center of the hub. It can be precise or it can be an eyeball, and I think with these small differences you may want it to be as precise as possible? I originally held a tape measure up to to my wheel and tried to figure out how to get an accurate measurement from the center of the hub when that center is six inches in from the wheel. I ended up using a level and doing some calculations. Maybe I'm just dumb and couldn't figure out a simple way, but originally eyeballing it with just the tape measure I guessed 16".

...
Blaine's method using Grimmjeeper.com beginning here...
https://wranglertjforum.com/threads/what-is-your-nominal-ride-height.16717/page-4#post-277228
...is going to be the most accurate as well as the most broadly informative beyond this discussion. Measuring the axle as described earlier is also very good. I took my first measurement with a tape measure and a level off of the hub, which was quite close to Grimmjeeper (either by luck or skill).
 
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Jerry Bransford

TJ Guru
Supporting Member
Nov 9, 2015
10,958
Escondido California
I don't understand how it could be difficult to find the precise center of the hub. I really don't.

The center of the hub is half-way between the top & bottom of the wheel. Not around half-way, precisely half-way. I.E. 7.5" up from the bottom of a 15" wheel.
 
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Mr. Bills

TJ Addict
Nov 24, 2017
1,562
Area Code 530
315/75R16 (Mickey Thompson Baja ATZ P3) mounted on 16x8 wheels
Load Range E
Manufacturer's Advertised Diameter - 34.5" @ 65 psi measured on 8.5" wide wheel
Manufacturer's Advertised Tread Depth - 18.5/32"
Measured Hub Height - 15.75"
Measured Tread Depth - 14/32"
Measured PSI - 22 psi @ 37 degrees ambient temperature (tires last filled/pressure checked at 26 psi when ambient temperatures were in the 70's).
Weight of Jeep - unknown.

I hope this information helps, but my thinking is that the hub height data being collected cannot yield usable results without knowing the weight of the jeeps being measured because the loaded radius of a tire will change as the load on that tire increases. In other words, when measuring the hub heights of two jeeps with identical tires on identical rims with identical air pressure in the tires, the hub height of the jeep weighing more will be less due to the increased load on the tires.
 
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toximus

TJ Addict
Supporting Member
Mar 29, 2018
2,247
Northern WI
315/75R16 (Mickey Thompson Baja ATZ P3) mounted on 16x8 wheels
Load Range E
Manufacturer's Advertised Diameter - 34.5" @ 65 psi measured on 8.5" wide wheel
Manufacturer's Advertised Tread Depth - 18.5/32"
Measured Hub Height - 15.75"
Measured Tread Depth - 14/32"
Measured PSI - 22 psi @ 37 degrees ambient temperature (tires last filled/pressure checked at 26 psi when ambient temperatures were in the 70's).
Weight of Jeep - unknown.

I hope this information helps, but my thinking is that the hub height data being collected cannot yield usable results without knowing the weight of the jeeps being measured because the loaded radius of a tire will change as the load on that tire increases. In other words, when measuring the hub heights of two jeeps with identical tires on identical rims with identical air pressure in the tires, the hub height of the jeep weighing more will be less due to the increased load on the tires.
You forgot the elevation and moon phase and it's effect on gravity.
 

bobthetj03

vibrajeep
Supporting Member
Ride of the Month Winner
Feb 3, 2017
8,942
NorCal
315/75R16 (Mickey Thompson Baja ATZ P3) mounted on 16x8 wheels
Load Range E
Manufacturer's Advertised Diameter - 34.5" @ 65 psi measured on 8.5" wide wheel
Manufacturer's Advertised Tread Depth - 18.5/32"
Measured Hub Height - 15.75"
Measured Tread Depth - 14/32"
Measured PSI - 22 psi @ 37 degrees ambient temperature (tires last filled/pressure checked at 26 psi when ambient temperatures were in the 70's).
Weight of Jeep - unknown.

I hope this information helps, but my thinking is that the hub height data being collected cannot yield usable results without knowing the weight of the jeeps being measured because the loaded radius of a tire will change as the load on that tire increases. In other words, when measuring the hub heights of two jeeps with identical tires on identical rims with identical air pressure in the tires, the hub height of the jeep weighing more will be less due to the increased load on the tires.
Be careful! You'll be accused of requesting Nano-measurements! :nono:
 

tworley

TJ Addict
Supporting Member
Ride of the Month Winner
May 23, 2018
2,269
Morrison, CO
Where's the thread that includes frame height with lift/tire combos? Im curious about something....
 
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jjvw

jjvw

0-60 in 18 seconds
Supporting Member
Feb 17, 2018
6,654
Colorado, USA
Bumping for more data.

I want to post the latest chart soon. More data is more helpful. :)

Load range E tires are especially needed.

Thanks all!
 

pagrey

TJ Enthusiast
Apr 10, 2018
780
Los Angeles, CA, USA
I don't understand how it could be difficult to find the precise center of the hub. I really don't.

The center of the hub is half-way between the top & bottom of the wheel. Not around half-way, precisely half-way. I.E. 7.5" up from the bottom of a 15" wheel.
!5" wheels are 16" in diameter, maybe it's more difficult than you think...
 

mrblaine

TJ Expert
Supporting Member
Nov 20, 2015
5,334
Quail Valley, CA
!5" wheels are 16" in diameter, maybe it's more difficult than you think...
A 15" wheel as in if you are measuring the hub height of a rig with that size rim. Halfway between the two edges of the rim of any size will give you the center of that rim. So, for the dimensionally impaired, you would measure the overall diameter of the rim no matter what size it is, divide that by 2 and write it down. Then you measure from the ground up to the same edge of the rim you used to measure the overall diameter. Now write that down under the first number you wrote down. Now, add those two together and write that down and put a circle around it.

When you post up your hub height, use only the number you circled.

That said, 15" wheels are not 16" in diameter or they would be called 16" wheels. The diameter of any automotive wheel we use is measured at the spot where the tire beads sit. The bead lips may measure larger than the rim diameter but that doesn't change the size of the wheel which is what size tire fits on it.
 

toximus

TJ Addict
Supporting Member
Mar 29, 2018
2,247
Northern WI
For the khaki TJ:

What is your tire size printed on the sidewall? 35x12.5x17
What is your hub height? 16.5"
What is your psi? 26psi
What is your load range? D
 

Mr. Bills

TJ Addict
Nov 24, 2017
1,562
Area Code 530
What is your tire size printed on the sidewall?
What is your hub height?
What is your psi?
What is your load range?
Size: 315/75R16 Mickey Thompson Baja ATZ P3 - a "metric 35" with advertised diameter of 34.5"
Hub Height: 15.75" (17" to top of front axle tube - 1.25")
Tire Pressure: 26 psi (measured with Accugage 0-60 psi gauge at 564' elevation, 75*F ambient temperature)
Load Range: E

Note: This is the same hub height as when measured 1/4/19 at the same elevation but 22 psi and 37*F ambient temperature.


For an illuminating discussion of the effect of elevation on tire pressure and tire "footprint" see this from Harry Llewellyn at Coyote Enterprises, which also includes a handy calculator: https://www.coyoteents.com/compensating-pressure-gauge-readings-altitude/
 
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S.McArthur

TJ Enthusiast
Supporting Member
May 31, 2018
622
Greenbrier, TN
What is your tire size printed on the sidewall? 33x12.50R17LT
What is your hub height?
**Ground to center w/eyeballs: 15.25" / Blaine's method: 15.5"
What is your psi? 27
What is your load range? D


33x12.50R17LT
15.5"
27
D
 
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OP
jjvw

jjvw

0-60 in 18 seconds
Supporting Member
Feb 17, 2018
6,654
Colorado, USA
Keep the data coming. I'll make a new chart soon. Also look for the nominal frame height thread and contribute your data there as well.
 
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