Rubicon equivalent tires on Sahara rims

Michael A

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Knowledgeable people: If I get a Sahara, can I keep the same rims and install larger tires, equivalent to the Rubicon diameter?





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Dogboyslim

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265/70/18 is pretty much the same diameter, but is about an inch narrower. 275/70/18 is a hair larger diameter (1.5%ish) and is about half an inch narrower.

EDIT: This is in reference to the stock Rubicon Tire size. I see now that the OP meant matching the stock Sahara tire size.

On a personal note, I have run Stock Rubicon Tires and Stock Sahara tires with the factory Speedo settings. The Rubicon stock size had me going 62 mph GPS speed (the original setting as sold from the factory to me). When I put the Stock Sahara tires on (which I purchased before building up) I ran true GPS speed. I say this only because I suggest before you buy a tazer, download Waze or another GPS device and measure your true speed against the speedo to see if an adjustment is necessary. Also, keep track of the difference, it will help you get the diameter correct. So if Speedo is 60 and you are going 62, 62/60 = 1.033. When you go into the tazer, it will tell you the stock diameter setting. Mulitply that number by 1.033 and set the new setting to the value closest to that. When I put the 315's on, I was able to hit GPS speed with 1 adjustment. Good luck!
 
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Michael A

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The Sahara I am looking at has 255/70R18.
 
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Michael A

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I am more concerned about the diameter than the width as how it will affect the speedometer, it seems they are pretty close.


255/70-18:285/70-17 Difference
Diameter inches (mm)
32.06 (814.2): 32.71 (830.8) 0.65 (16.6) 2%
Width inches (mm)
10.04 (255) :>11.22 (285) 1.18 (30) 11.8%
Circum. inches (mm)
100.7 (2557.88): 102.76 (2610.04) 2.05 (52.15) 2%
Sidewall Height inches (mm)
7.03 (178.5):7.85 (199.5) 0.83 (21) 11.8%
Revolutions per mile (km)
629.17 (390.95):616.6 (383.14) -12.57 (-7.81) -2%

Speedometer Difference
Speedo Reading Actual Speed
20 mph (32.19 km/h) 20.41 mph (32.84 km/h)
25 mph (40.23 km/h) 25.51 mph (41.05 km/h)
30 mph (48.28 km/h) 30.61 mph (49.26 km/h)
35 mph (56.33 km/h) 35.71 mph (57.48 km/h)
40 mph (64.37 km/h) 40.82 mph (65.69 km/h)
45 mph (72.42 km/h) 45.92 mph (73.9 km/h)
50 mph (80.47 km/h) 51.02 mph (82.11 km/h)
55 mph (88.51 km/h) 56.12 mph (90.32 km/h)
60 mph (96.56 km/h) 61.22 mph (98.53 km/h)
65 mph (104.61 km/h) 66.33 mph (106.74 km/h)

 

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I am more concerned about the diameter than the width as how it will affect the speedometer, it seems they are pretty close.


255/70-18:285/70-17 Difference
Diameter inches (mm)
32.06 (814.2): 32.71 (830.8) 0.65 (16.6) 2%
Width inches (mm)
10.04 (255) :>11.22 (285) 1.18 (30) 11.8%
Circum. inches (mm)
100.7 (2557.88): 102.76 (2610.04) 2.05 (52.15) 2%
Sidewall Height inches (mm)
7.03 (178.5):7.85 (199.5) 0.83 (21) 11.8%
Revolutions per mile (km)
629.17 (390.95):616.6 (383.14) -12.57 (-7.81) -2%

Speedometer Difference
Speedo Reading Actual Speed
20 mph (32.19 km/h) 20.41 mph (32.84 km/h)
25 mph (40.23 km/h) 25.51 mph (41.05 km/h)
30 mph (48.28 km/h) 30.61 mph (49.26 km/h)
35 mph (56.33 km/h) 35.71 mph (57.48 km/h)
40 mph (64.37 km/h) 40.82 mph (65.69 km/h)
45 mph (72.42 km/h) 45.92 mph (73.9 km/h)
50 mph (80.47 km/h) 51.02 mph (82.11 km/h)
55 mph (88.51 km/h) 56.12 mph (90.32 km/h)
60 mph (96.56 km/h) 61.22 mph (98.53 km/h)
65 mph (104.61 km/h) 66.33 mph (106.74 km/h)

The Bigger issue when you go to the wider tire is the stock wheel sets too far inside the wheel well, taller wider when you need to lose the stock Sahara wheels. Instead just sell your stock wheels and Tires $500-$600 buy a set of Rubicon Takeoffs for $800-$1000 you will have tires and wheels that match... Rubicon take off are easy to find
 
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Michael A

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Appreciate all of your inputs, new to the 4-wheeling scene.
 

Arterius2

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Appreciate all of your inputs, new to the 4-wheeling scene.
I think if you just invested in a programmer (Tazer JL or Flashcal) you wouldn't have to worry about your speedometer.

If you want to avoid tires rubbing on your suspension, you DO NOT want to go wider than 285 on stock wheels.
@Dogboyslim post above gave you a good suggestion, 275/70/18 is a good size on stock hardware.

For some comparisons on stock 18” wheels.

This is 275/70R18 (33") on my Sahara back in the days:
C01E64E9-43F7-4EAB-B966-81B9D4386955.jpeg


And this is 285/75R18 (35") on my Sahara now:
4499A579-C224-468D-B78E-3CF637D05D16.jpeg
 
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Revolution_322

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Yes but 18” rims offer less sidewall. More companies offer 35 37 and ip in 18 “ rim
 

TrailJoy

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If you want to avoid tires rubbing on your suspension, you DO NOT want to go wider than 285.
@Dogboyslim post above gave you a good suggestion, 275/70/18 is a good size on stock hardware.
Just to note (and for my own clarification), the rubbing mentioned is on stock wheels, which have a +44.5 offset. We recently switched to a -12 offset and are looking to switch (this afternoon, actually) again to +18 as the tires do extend out quite a bit. I'm HOPING there won't be any rubbing issues with the wider tires, but as mentioned, the example is with the stock wheels. The difference in offset does make a difference. Also, when we bought our tires, we had a helluva time finding 275's on 17" wheels (in the right size), which is why we went with 285. I don't know how common that size is for 18" wheels.

Just food for thought (or should you decide to switch it up later). :)

Editing for clarification. We bought 285/70R17, which is only .6" bigger than the stock Sahara tires (255/70R18).
 

Av_86

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I think if you just invested in a programmer (Tazer JL or Flashcal) you wouldn't have to worry about your speedometer.

If you want to avoid tires rubbing on your suspension, you DO NOT want to go wider than 285 on stock wheels.
@Dogboyslim post above gave you a good suggestion, 275/70/18 is a good size on stock hardware.

For some comparisons on stock 18” wheels.

This is 275/70R18 (33") on my Sahara back in the days:
C01E64E9-43F7-4EAB-B966-81B9D4386955.jpeg


And this is 285/75R18 (35") on my Sahara now:
4499A579-C224-468D-B78E-3CF637D05D16.jpeg
Lift?
 

NewJLU2019

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The Sahara I am looking at has 255/70R18.
I kept my Stock wheels and friend at 4 Wheel parts recommend the BFG KO2's 33's 275/70R/18. Since Stock wheels are 18 / 7.5 lot of bigger tires require a wider wheel than 7.5 He recommended the Tearflex spacer kit to give more room for tires and off-road use. The front 2.0 inch removed Factory Nose rakes Jeeps have and the 1.5 rear leveled her out. Gave the more Aggressive stance Jeep look you want. BFG KO2's are E-rated so he put 34PSI that makes the ride much better than factory 41 PSI.

Before Lift &  33'.jpg


Donut Place.jpg


Cool Weather.jpg
 

Av_86

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Looks awesome , thanks..
 

pkilinj

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I kept my Stock wheels and friend at 4 Wheel parts recommend the BFG KO2's 33's 275/70R/18. Since Stock wheels are 18 / 7.5 lot of bigger tires require a wider wheel than 7.5 He recommended the Tearflex spacer kit to give more room for tires and off-road use. The front 2.0 inch removed Factory Nose rakes Jeeps have and the 1.5 rear leveled her out. Gave the more Aggressive stance Jeep look you want. BFG KO2's are E-rated so he put 34PSI that makes the ride much better than factory 41 PSI.

Before Lift &  33'.jpg


Donut Place.jpg


Cool Weather.jpg
Did you notice a big drop in MPG or power loss ?
 

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