changing tires size & how to correct?????
1 - 13 of 13 Posts
Assuming you have 31.5 stock tires right now, the error is equal to
38/31.5 = 1.2
Or, 20%. So if your speedo shows 50, you'll really be doing 60. You have a few options:
1) Get one of the tuners that allows speedo correction
2) Get a cheaper speed corrector, or visit the Ford dealer, I heard they will do it also.
3) Do nothing and just use the rule "take mph on speed, divide by 10 and double it" then add that to what the speedo shows.
For example, 60 on speed: 60/10 = 6...double that is 12....add that to 60, you get 72. So your real speed is 72 mph
Why would you want option 3? Your odometer will show less miles. If you correct it, then the miles your tires see is what is registered on the odometer, while your engine actually only did 20% less rpms/etc. Helps resale value, etc. The rule is very easy, you'll get accostomed to it FAST.
RL
38/31.5 = 1.2
Or, 20%. So if your speedo shows 50, you'll really be doing 60. You have a few options:
1) Get one of the tuners that allows speedo correction
2) Get a cheaper speed corrector, or visit the Ford dealer, I heard they will do it also.
3) Do nothing and just use the rule "take mph on speed, divide by 10 and double it" then add that to what the speedo shows.
For example, 60 on speed: 60/10 = 6...double that is 12....add that to 60, you get 72. So your real speed is 72 mph
Why would you want option 3? Your odometer will show less miles. If you correct it, then the miles your tires see is what is registered on the odometer, while your engine actually only did 20% less rpms/etc. Helps resale value, etc. The rule is very easy, you'll get accostomed to it FAST.
RL
I have not heard of any tuner on market for the 6.0 diesel that can adjust speedo for tire size or gear ratio.....they will do it on gasers but not for the 6.0........tell me if I am wrong I will buy it because I would love to be able to do that with mine.
Tim
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For 38" tires you're going to need a True Speed to correct your speedo.
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If he wants to.......and some of the tuners can do it too.
RL
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Tim
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For 38" tires you're going to need a True Speed to correct your speedo.
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If he wants to.......and some of the tuners can do it too.
RL
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Talked to them today and they cannot calibrate the speedometer but they can change shift points. They recommended getting a superlift truespeed to calibrate speedo.....Tim
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Innovative and ATS can build you a custom tune that will calibrate speedometer and shift points. I went with Innovative, but I have heard good things about both.
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Innovative and ATS can build you a custom tune that will calibrate speedometer and shift points. I went with Innovative, but I have heard good things about both.
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Please tell us which tuner will calibrate for speed since I talked to ATS and innovative SCT and they cannot change speedo which is what I already said and I have used superchip and predador and bully dog which is my current tuner and none of them can change speedometer so please tell me which one will?????
Tim
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If you don't want to use a tuner, Ford can calibrate for up to 35" tires. This will atleast get you close.
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Tim
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If you don't want to use a tuner, Ford can calibrate for up to 35" tires. This will atleast get you close.
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Ok, I dug around, look here:
http://www.sctflash.com/xc2.php
Scroll down, center column. You can play with axle ratio (2.73 to 5.14) and tire size (205/65/15 to 315/35/19). Me thinks the SCT CAN do tires......maybe whoever you spoke with at Innovative was misinformed (or SCT's website is misleading).....
So, can anyone confirm whether the new SCT can do tire sizes???
RL
http://www.sctflash.com/xc2.php
Scroll down, center column. You can play with axle ratio (2.73 to 5.14) and tire size (205/65/15 to 315/35/19). Me thinks the SCT CAN do tires......maybe whoever you spoke with at Innovative was misinformed (or SCT's website is misleading).....
So, can anyone confirm whether the new SCT can do tire sizes???
RL
Joined
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2,072 Posts
SCT can adjust the speedo for tire size on all electronically controlled speedometers read from the processor. The Diesel trucks speedometer do not read MPH from the computer, therefore we can't adjust. However we do make tire size adjustment for proper part throttle shift points. Virtually all 1996+ Ford vehicles can be changed within the programming, except the Diesel's. The dealer can make a change to adjust for tire size up to about a 33" tire, it's the revs stored in the ID Block.
The simplest way to adjust is by using the Superlift module.
The simplest way to adjust is by using the Superlift module.
It adjusts for shifting but speedo will still be off on the diesels....Tim
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Ok, I dug around, look here:
http://www.sctflash.com/xc2.php
Scroll down, center column. You can play with axle ratio (2.73 to 5.14) and tire size (205/65/15 to 315/35/19). Me thinks the SCT CAN do tires......maybe whoever you spoke with at Innovative was misinformed (or SCT's website is misleading).....
So, can anyone confirm whether the new SCT can do tire sizes???
RL
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Ok, I dug around, look here:
http://www.sctflash.com/xc2.php
Scroll down, center column. You can play with axle ratio (2.73 to 5.14) and tire size (205/65/15 to 315/35/19). Me thinks the SCT CAN do tires......maybe whoever you spoke with at Innovative was misinformed (or SCT's website is misleading).....
So, can anyone confirm whether the new SCT can do tire sizes???
RL
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