Yeret
The Village Drunk
- Joined
- Oct 2, 2014
- Posts
- 943
- Reaction score
- 178
- Ram Year
- 1999
- Engine
- 5.9 Magnum
Hey folks, seems it's been a damned queen's age since I last posted here. Not a whole lot has really happened in regards to the ole Ram, which isn't necessarily a bad thing, LOL.
Anywho, while poking around Hughes Engines to do some research on Victor cylinder heads (for an entirely different engine/application of course), I came across this article stating that big tires on a truck that hasn't been reprogrammed to factor in the larger tires will result in the computer screwing with the engine parameters with damaging resolve. You can read here...
http://www.hughesengines.com/Index/bigtires.php
Is there really truth to this? For one, I didn't think that the computer used the vehicle's speed as a factor for adjusting operating parameters. And two, I know in our trucks that the computer uses the speed sensor in the rear axle to calculate speed. Now, this sensor sends pulses to the computer as a result of the toothed tone ring and the Hall effect. Since the tone ring is affixed to the axle shaft rather than the wheel, would changing the tire size really effect it's rotational speed? Same goes for the ring and pinion as well. I was always under the impression that swapping the tire size wouldn't affect the output speeds of the transmission, axle gears and the related sensors but the tires themselves would change speed depending on whether they're taller or shorter. I mean, 70 MPH is 70 MPH irregardless of tire size, right? If the tires are taller, they're gonna rotate slower but the vehicle is still moving at whatever speed the speedo shows, right?
Or am I just totally wrong on all this? Quite frankly, as much conflicting stuff as I've read on changing the tire size from OEM, I've never been absolutely certain about the effects on output speeds on the drivetrain. Educate me if I'm wrong, dudes!
Anywho, while poking around Hughes Engines to do some research on Victor cylinder heads (for an entirely different engine/application of course), I came across this article stating that big tires on a truck that hasn't been reprogrammed to factor in the larger tires will result in the computer screwing with the engine parameters with damaging resolve. You can read here...
http://www.hughesengines.com/Index/bigtires.php
Is there really truth to this? For one, I didn't think that the computer used the vehicle's speed as a factor for adjusting operating parameters. And two, I know in our trucks that the computer uses the speed sensor in the rear axle to calculate speed. Now, this sensor sends pulses to the computer as a result of the toothed tone ring and the Hall effect. Since the tone ring is affixed to the axle shaft rather than the wheel, would changing the tire size really effect it's rotational speed? Same goes for the ring and pinion as well. I was always under the impression that swapping the tire size wouldn't affect the output speeds of the transmission, axle gears and the related sensors but the tires themselves would change speed depending on whether they're taller or shorter. I mean, 70 MPH is 70 MPH irregardless of tire size, right? If the tires are taller, they're gonna rotate slower but the vehicle is still moving at whatever speed the speedo shows, right?
Or am I just totally wrong on all this? Quite frankly, as much conflicting stuff as I've read on changing the tire size from OEM, I've never been absolutely certain about the effects on output speeds on the drivetrain. Educate me if I'm wrong, dudes!