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dodgesalesguy
Dodge Dakota
JOIN HERE
9/05/2002
15:48:55
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 Subject: speedometer and tires
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when going to 33 inch tires on a 15 inch rim, what is the effect on the speedometer and odometer?
just wondering what to expect when i do the lift and tires.
thanks
fred garza
00 dak quad 4x4
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dweishaar
GenIII
9/05/2002
16:12:02
|  RE: speedometer and tires
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i divide by 3 and multiply by 4. i have 33x1250's
One Eyed Fox
The Baja Dak
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Dan Gruber
GenIII
9/05/2002
16:46:03
| RE: speedometer and tires
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Depends on the size of the original tires. If your stock tires were the 235's, your speedo will read about 10-11% low. If your stock tires were the 31's, it will be about a 5-6% difference. Thrown into the mix is the fact that depending on tire manufacturer, a 33 inch tire (for example only) could range in actual diameter from just over 32 to well over 33 inches. According to Goodyear's own data (from their website) my original 31 inch Wranglers had diameter of 30.4 inches. But my current 32 inch BFG Mudds as measured by BFG are 31.9 inches. So what I thought was a 1 inch increase in diameter was acturally 1.5 inches. It might sound like I'm getting picky, but a half inch difference plays into speedo error as well as fender clearance.
The dealer can reprogram the computer for larger tires, but only for tire sizes that were offered by the factory. So if your truck originally had the 235's, the dealer can reprogram for the 31's to decrease the amount of speedo error...it'll still read low, but not as bad. Or there is a speedo recalibrator available from superlift that is supposed to be able to correct it entirely. Not sure if or how it works. And I believe in 99 Dodge switched to an electronic sensor rather than a mechanical gear driven speed system, so you can't just change the speedo gearing like older trucks can.
Dan
2000 CC SLT 4.7 4X4 Auto 3.92 LSD
3 inch Performance Accesories lift & 32 inch BFG MT KM's
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forexfour
GenIII
9/09/2002
12:45:33
| RE: speedometer and tires
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I have done some research here. I have finally installed the Superlift speed recalibrator. If you run larger tires you should have this. After running on 33's for the last few months the performance and the shifting (auto) was terrible. Trip mileage was off. Now I have fine tune calibrated within .10 MPH as per GPS speed check on 33's. Easy install if you have a service manual. If not finding the wires can be tough but I know how and where to hook into. For the $150 I think it was worth it.
The local dealer did tell me that they could get a different PCM or something to for the 4.7 and 5.9's but not the 3.9's. Since they did not have them for mine I did not look into it any further.
From 31's to 33's I ran about 17 miles less per tank and speed was off from 3-6 MPH depending on how fast you are going.
Still on stock suspension! No rubbing! Right DJ?
FXF
Never late for a Tee time or wheelin with my buddies! Always ready for both!!!Forexfour's home page.
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RESQready
GenIII
9/09/2002
13:00:12
| RE: speedometer and tires
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I see you kept busy this weekend. And you're right, no rubbing! It took a few good off-road trips to find all the trouble spots, but some creative trimming, a torsion bar crank, and a little modification to the stock bumper = 33's with out a lift.
What's really goin' on?
RESQready Dakota
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josh
Dodge Dakota
JOIN HERE
9/10/2002
22:30:26
|  RE: speedometer and tires
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hahaha boys boys boys. i get a kick reading some of ya's answers when all you have to do is just go looking for it on the net and leave it up to the pros to do all the figureing go here to get the right figures http://www.tyres1.com/tech_calcs.html hahahahahah you guys are funny as hell.
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forexfour
GenIII
9/11/2002
10:51:54
| RE: speedometer and tires
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I don't get what is so funny in our responses. I have done the research through these types of web sites and I think that us generalizing this info for those looking for a quick answer appriciate it. That's is why they come here. I can barley find what I am looking for through the web but guys here will send you to it.
I believe the answer was 7% to the original question or if you are going 65 mph indicated you are really doing 69-70. This was not obtained from your recommended site just research from post I had previously read and my own personal experience.
I guess the joke is on us or me. HAHA!
BTW Dodgesalesguy,
Did you get what you were looking for?
FXF
Never late for a Tee time or wheelin with my buddies! Always ready for both!!!Forexfour's home page.
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TallQuad
Dodge Dakota
JOIN HERE
9/14/2002
16:44:25
| RE: speedometer and tires
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Message:
From stock to 33's I'm around 13% off. At 100 mph on the speedo. I would really going 113 mph (not that I go that fast!). I forgot the tire size that comes with the T&H package, but its what comes with a 2wd, 4.7, with 3.92s.
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