Tire Conversion Chart.

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powerhour

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i hope this helps!

225/85R 14 = 29 X 9.00 X 14
215/75R 15 = 28 X 8.50 X 15
215/85R 15 = 29 X 8.50 X 15
225/75R 15 = 28 X 9 X 15
235/75R 15 = 29 X 9 X 15
325/60R 15 = 31 X 12.50 X 15
Q78-15 = 35.50 X 11.00 X 15
215/70R 16 = 28 X 8.50 X 16
225/70R 16 = 28.50 X 9 X 16
225/75R 16 = 30 X 9 X 16
235/70R 16 = 29 X 9.50 X 16
235/85R 16 = 32 X 9.50 X 16
245/70R 16 = 30 X 10 X 16
245/75R 16 = 31 X 10 X 16
255/70R 16 = 30 X 10.50 X 16
255/85R 16 = 33 X 10.50 X 16
265/70R 16 = 31 X 10.50 X 16
265/75R 16 = 32 X 10.50 X 16
265/80R 16 = 32.50 X 10.00 X 16
275/70R 16 = 31.50 X 11 X 16
285/75R 16 = 33 X 11.50 X 16
295/75R 16 = 33.50 X 12 X 16
305/70R 16 = 33 X 12.50 X 16
305/85R 16 = 36 X 11.50 X 16
315/75R 16 = 35 X 12.50 X 16
325/70R 16 = 34 X 13 X 16
325/80R 16 = 37 X 13 X 16
365/65R 16 = 35 X 14.50 X 16
Q78-16 = 35.50 X 11.00 X 16
265/70R 17 = 32 X 11.50 X 17
275/70R 17 = 32.50 X 11.00 X 17
285/70R 17 = 33 X 11.50 X 17
295/70R 17 = 33 X 12.0 X 17
305/70R 17 = 34 X 12.00 X 17
315/70R 17 = 34.50 X 12 X 17
255/55R 18 = 29 X 10.50 X 18
285/60R 18 = 32 X 11 X 18
285/65R 18 = 33 X 11.50 X 18
325/60R 18 = 33 X 13 X 18
325/65R 18 = 35 X 13 X 18
355/65R 18 = 37 X 14 X 18
305/50R 20 = 32 X 12.50 X 20
305/55R 20 = 33 X 12.50 X 20
325/60R 20 = 35 X 13.00 X 20
355/60R20 = 36.50 X 14.00 X 20
325/50R22 = 35 X 13.00 X 22
 

glass3222

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Good info.

Or if you want to convert it yourself:

1. take the first number (the width in millimeters) and divide by 25.4, this give you the width in inches

2. multiply be the second number (aspect ratio) divide by 100 (percentage), this gives you the sidewall height

3. multiply by 2, the add the 3rd number (wheel diameter)

Example: 275/60 R20 (factory 20" Ram tires)

1. 275/25.4= 10.82677 inches

2. 10.82677*60/100 or 10.82677/.6 = 6.496 inches

3. 6.496*2 = 12.992 + 20 = 32.992 = 33" tire height.
 

Deviate

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That chart and formula will get you in the ballpark, but depending on the manufacturer the actual tire height will vary because of tread pattern or what have you. Case in point:

265-70-17 AT tires:
Formula Height: 31.61
Nitto Terra Grappler actual height: 31.57
BFG AT: 31.8
**** Cepek Radial F-C II: 31.7

Not that a 10th of an inch makes that much real world difference, but just pointing that out.
 

ramhunter9

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good info fellas .. stickie time
 

Birddog

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i hope this helps!

225/85R 14 = 29 X 9.00 X 14
215/75R 15 = 28 X 8.50 X 15
215/85R 15 = 29 X 8.50 X 15
225/75R 15 = 28 X 9 X 15
235/75R 15 = 29 X 9 X 15
325/60R 15 = 31 X 12.50 X 15
Q78-15 = 35.50 X 11.00 X 15
215/70R 16 = 28 X 8.50 X 16
225/70R 16 = 28.50 X 9 X 16
225/75R 16 = 30 X 9 X 16
235/70R 16 = 29 X 9.50 X 16
235/85R 16 = 32 X 9.50 X 16
245/70R 16 = 30 X 10 X 16
245/75R 16 = 31 X 10 X 16
255/70R 16 = 30 X 10.50 X 16
255/85R 16 = 33 X 10.50 X 16
265/70R 16 = 31 X 10.50 X 16
265/75R 16 = 32 X 10.50 X 16
265/80R 16 = 32.50 X 10.00 X 16
275/70R 16 = 31.50 X 11 X 16
285/75R 16 = 33 X 11.50 X 16
295/75R 16 = 33.50 X 12 X 16
305/70R 16 = 33 X 12.50 X 16
305/85R 16 = 36 X 11.50 X 16
315/75R 16 = 35 X 12.50 X 16
325/70R 16 = 34 X 13 X 16
325/80R 16 = 37 X 13 X 16
365/65R 16 = 35 X 14.50 X 16
Q78-16 = 35.50 X 11.00 X 16
265/70R 17 = 32 X 11.50 X 17
275/70R 17 = 32.50 X 11.00 X 17
285/70R 17 = 33 X 11.50 X 17
295/70R 17 = 33 X 12.0 X 17
305/70R 17 = 34 X 12.00 X 17
315/70R 17 = 34.50 X 12 X 17
255/55R 18 = 29 X 10.50 X 18
285/60R 18 = 32 X 11 X 18
285/65R 18 = 33 X 11.50 X 18
325/60R 18 = 33 X 13 X 18
325/65R 18 = 35 X 13 X 18
355/65R 18 = 37 X 14 X 18
305/50R 20 = 32 X 12.50 X 20
305/55R 20 = 33 X 12.50 X 20
325/60R 20 = 35 X 13.00 X 20
355/60R20 = 36.50 X 14.00 X 20
325/50R22 = 35 X 13.00 X 22

Great post. That's a lot of typing!

Sent from my Note 3 using Tapatalk Pro!
 

2012Outdoorsman5.7

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I keep trying to figure out for the tires im planning on buying but dosent seem right, Let me know what you guys get.

285/65/20

295/65/20


Thanks.
 

R.L.K.

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Wow ! Thanks
 

16RamBlackOut

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i am still lost when it comes to this, between the sizing and offset I am just going to not change anything. There has to be a chart somewhere that shows you what will work/fit without changing suspension geometry and requiring recalibration of your speedo.

I have stock 20" on my big horn by window sticker says they are 20x8 the tire size converts to 10.8" wide (275/65R20) I am not sure what is right. I cant find the stock offset either.

I just want to put some 24" SRT replicas on it, they are 10" wide and +25.4 offset on them, I am not sure if they will stick out further or what size tire i need to not screw with my speedo. I guess this is why dumb people (me) pay smart people to do this stuff for them.
 

R.L.K.

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The diameter of your wheel has nothing to do with your speedometer , the diameter of your tire will change the speedometer . If you get the same diameter tire you'll be fine there .
As far as offset , maybe a smart guy will chime in that knows the offset & back spacing of your stock wheels and the replicas you want . I'd say most likely your 20x8 wheels are a + offset or " 0 " even though the replicas are 10" wide you say they are + 25.4mm offset = you'll most likely only be approximately 3/4" to 1" further out @ the wheels , this will also change with the tire width you choose ...
Come on smart guys where are ya ?
 

16RamBlackOut

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found a web site that will break down all the math if you get all of your info for your old and new setup.

willtheyfit.com and yes its SFW
 

Bigge2511

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Rims and tire issue

I have a 2016 ram 1500. Stock size is 20x9 with a 275/60/20 tire. I am putting in a 20x9 rim and same size tire but the offset is -12. Will these rub if I don't have. A level kit installed. Everyone keeps saying you have to put them in to see
 

R.L.K.

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I have a 2016 ram 1500. Stock size is 20x9 with a 275/60/20 tire. I am putting in a 20x9 rim and same size tire but the offset is -12. Will these rub if I don't have. A level kit installed. Everyone keeps saying you have to put them in to see
That set up will work , the only possible time you would rub would be in Drive or Reverse @ full lock combined with a bottoming out bounce over very rough terrain.
So if you do not normally BOUNCE through rough terrain @ full lock Right or Left in Drive or Reverse then you will be fine .
 

Bigge2511

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I won't be going over any ruff terrain and we don't get that much snow. Full lock is 4 low I'm assuming
 

R.L.K.

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I won't be going over any ruff terrain and we don't get that much snow. Full lock is 4 low I'm assuming
Sorry , full lock is the steering wheel full right or full left
 

DRkNESS

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Here's where I am to be a pain lol. I currently have 20x9 wheels with oem fitment of 275/60 on them. I'm on Bilstein at 2.1. I want to go with a 295/60 tire to give a slighter fuller look. I don't want off road/ mud tires as I don't do any of that. My current tires are Michelin LTX which SUK in the snow even with 4x4. Does anyone have 295 or even a narrow 35" tire on this set up that they are willing to post photos and thoughts on please ?dfcfd34d8e167ce104faef2d63d31a1c.jpg


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