How to Change tire size to fix speedo

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betz
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How to Change tire size to fix speedo

Post by betz »

On my 2005 astro, is it possible to change the tire size in the computer so that the speedo isn't so far off?
2005 Chevy Astro AWD 108,000
4" lift from Overland Vans w/Rancho 5000's
Belltech Rear Anti-Sway bar (mounted on top of axle)
BFG AT KO 255 70 16

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Rear Belltech Sway bar
BFG ATs and spots that required trimming to make 'em fit
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Rebel
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Re: How to Change tire size to fix speedo

Post by Rebel »

This info might help ya out.

http://www.transmissioncenter.net/speed ... gQodv0KDwQ
89 Astro, 350 V-8, Shaved doors, Filled Slider, Corvette IRS, 94 Mustang GT Rack & Pinion(Thanks to Skip), Cad Tail lights from SoCalliV8 ( RIP) Miss you my friend.

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betz
I get chills without my van.
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Re: How to Change tire size to fix speedo

Post by betz »

I was under the impression that this was a setting that could be changed in the van's computer. I brought it to my shop today, but they have a new snap on scan tool that they don't know how to use yet. Thought that maybe someone else would know what to do.
2005 Chevy Astro AWD 108,000
4" lift from Overland Vans w/Rancho 5000's
Belltech Rear Anti-Sway bar (mounted on top of axle)
BFG AT KO 255 70 16

Image
Rear Belltech Sway bar
BFG ATs and spots that required trimming to make 'em fit
Top
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peter
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Re: How to Change tire size to fix speedo

Post by peter »

The solution to your problem is as simple as purchasing a Hypertech Power Programmer. Buy one for your truck and you'll be able to compensate for tires/gearing etc. As well, you can select different performance levels thru the same programmer. Real simple and a fun tool for the backyard mechanic! :supz:
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betz
I get chills without my van.
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Re: How to Change tire size to fix speedo

Post by betz »

Peter, do you have one of those? If so, what is the exact model so that I can be sure it will work?
2005 Chevy Astro AWD 108,000
4" lift from Overland Vans w/Rancho 5000's
Belltech Rear Anti-Sway bar (mounted on top of axle)
BFG AT KO 255 70 16

Image
Rear Belltech Sway bar
BFG ATs and spots that required trimming to make 'em fit
Top

Rebel
I plan to be buried in my van
I plan to be buried in my van
Posts: 2009
Joined: Thu Sep 14, 2006 7:24 am
Location: Evergreen, Al. 96 mile marker, where life is slow and there are no rules.

Re: How to Change tire size to fix speedo

Post by Rebel »

I was under the impression that this was a setting that could be changed in the van's computer.
Surprised Peter didn't inform you that I'd be last to know anything about the computer in our vehicles. :yawinkle:
89 Astro, 350 V-8, Shaved doors, Filled Slider, Corvette IRS, 94 Mustang GT Rack & Pinion(Thanks to Skip), Cad Tail lights from SoCalliV8 ( RIP) Miss you my friend.

VIDEO

Image





If you drive illegally, they take your driver's license. If you're here illegally, they want to give you one :)












Image





If guns kill people, do pencils misspell words
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phr1$k37
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Re: How to Change tire size to fix speedo

Post by phr1$k37 »

betz wrote:Peter, do you have one of those? If so, what is the exact model so that I can be sure it will work?

I have the JetChips Super Programmer to change shift points, tire size and fuel rating (which is now back to low octane lol). I really did not see any performance except at WOT and even then it was super great. But the tranny stuff - THAT worked and is worth it imo. As well I have the vette servo in :)
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betz
I get chills without my van.
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Re: How to Change tire size to fix speedo

Post by betz »

Just wanted to mention I got the hypertech energy max. This thing is great. I was able to adjust my tire size, so the speedo is pretty darn accurate now. I have also been having a fun time messing with my shift points and what not. It is also great to be able to read my own codes and clear them when needed...like when the gas cap doesn't seal properly!
2005 Chevy Astro AWD 108,000
4" lift from Overland Vans w/Rancho 5000's
Belltech Rear Anti-Sway bar (mounted on top of axle)
BFG AT KO 255 70 16

Image
Rear Belltech Sway bar
BFG ATs and spots that required trimming to make 'em fit
Top
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