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Unread 07-18-2013, 10:16 PM   #1
Bigtom04
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2000 WJ 
 
Join Date: Jul 2013
Location: BAyonne, nj
Posts: 18
Tire decision

i know my jeep came with p245/70/16.. i was looking at the BFG All-Terrain T/A KO but i wanna do the LT245/75/16 that inch difference in height how bad will my speedo be off?? And If its off how can it be fixed? thank you

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Unread 07-19-2013, 04:24 AM   #2
mschi772
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1997 XJ Cherokee 
 
Join Date: Apr 2012
Location: Racine, WI
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You'll be traveling 3% faster than your speedometer says you are. For example, at 60 mph on your speedo, you'll actually be going 62; about 31 when speedo says 30.

To recalibrate the speedo/odometer (yes, trip and odometer readings will be wrong, too; even a 3% error can add-up to a pretty inaccurate odometer over time...if you care about that sort of thing), you need to reprogram the computer. There are tools you can get, or you can have a stealership do it for you for like $60-70ish.
Try THIS.
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Unread 07-19-2013, 06:34 AM   #3
Bigtom04
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Location: BAyonne, nj
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Thank you for your help, I'll talk to my local dealer and ask them about the recalibration, how much is the tool to do it myself? And you don't think there will be a rubbing issue do you?
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Unread 07-19-2013, 07:30 AM   #4
mschi772
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The size you're talking about getting is about 30.5". You may need to look up max tire size under a stock WJ to be sure because I'm not an expert on all things WJ, but I think you MIGHT be OK. Don't start a new thread asking if that tire size will fit--do a search. I'm sure it's been covered a TON already. I'm not sure about he tools' prices because my XJ doesn't use them--I merely have to pop a little gear in/out of my transfer case.
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Unread 07-19-2013, 07:40 AM   #5
WXman
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2001 WJ 
 
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WJs are notorious for having very little room for larger tires and for having springs that sag really bad over time. My advise would be to install a spacer lift first. You can do that for less than $150 bucks. Then you'll know for certain that you can go up 1 or 2 sizes with tires and be perfectly fine.
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Unread 07-19-2013, 08:28 AM   #6
Bigtom04
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I was already thinking of the 2" spring lift for the truck already... so I'll have to do some research cause I really want these tires for my jeep
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Unread 07-23-2013, 11:34 PM   #7
Charley3
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Your speedo might not be off at all.

I switched my XJ from 225/75R15 to 30 x 9.5 R15 tires (two tire sizes larger) and then used a GPS speedometer program that I loaded into my Android phone to check the XJ's speedometer.

It was dead on accurate with 30" tires. It must have been a bit off with the stock tires.

I suggest you use a GPS device, or a GPS program loaded into a smart phone, to test your speed and compare to your Jeep's speedometer.

Your speedometer might already be fine with 245/75R16 tires. My guess is that changing one tire size isn't enough to make it off.

Test it and find out.
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