Seeking directions / Advice on changing tire size from factory tires...

[BlueHemi1500]

Well thanks all for the most valuable information
I have been reading and learning. It has been a 3-week ordeal to get 2 new struts installed, parts have been a problem.
As of this Monday, my truck passed state inspection and has 2 new front struts 4 new tires, and a new front-end alignment.
I got the BRIDGESTONE DUELER A/T REVO 3 in the 275/60/R20 size. I have not driven but about 20 miles on the new tires, In my limited experience no obvious road noise difference, was noted from the factory tires Bridgestone Dueler H/L 275/55/R20.

So this coming Sunday, I will break out the bypass cable and plug it in, for me that is a challenge to accomplish, short arms, short stubby fingers, and just out of my field of vision. Once, I'm done with the truck yoga. I will make a few test runs to verify what the speedometer reads compared to a GPS speed program on the phone and make notes at various speeds. My wife will be driving so I can use the phone and make notes, stop in a safe place off the road make some changes, make notes, and make a test run and compare. Rinse and repeat, to get the readings as accurate as possible.
I work as a Paramedic/Firefighter so tickets are bad things for the work situation not to mention the insurance hit for speeding.
So stay tuned on this same bat channel for the next adventures of the BlueHemi1500 superhero.

BlueHemi1500

 

[HSKR R/T]

Well thanks all for the most valuable information
I have been reading and learning. It has been a 3-week ordeal to get 2 new struts installed, parts have been a problem.
As of this Monday, my truck passed state inspection and has 2 new front struts 4 new tires, and a new front-end alignment.
I got the BRIDGESTONE DUELER A/T REVO 3 in the 275/60/R20 size. I have not driven but about 20 miles on the new tires, In my limited experience no obvious road noise difference, was noted from the factory tires Bridgestone Dueler H/L 275/55/R20.

So this coming Sunday, I will break out the bypass cable and plug it in, for me that is a challenge to accomplish, short arms, short stubby fingers, and just out of my field of vision. Once, I'm done with the truck yoga. I will make a few test runs to verify what the speedometer reads compared to a GPS speed program on the phone and make notes at various speeds. My wife will be driving so I can use the phone and make notes, stop in a safe place off the road make some changes, make notes, and make a test run and compare. Rinse and repeat, to get the readings as accurate as possible.
I work as a Paramedic/Firefighter so tickets are bad things for the work situation not to mention the insurance hit for speeding.
So stay tuned on this same bat channel for the next adventures of the BlueHemi1500 superhero.

BlueHemi1500

If you are using alfaObd to change the speedometer, there is a tire change option that gives you a list of different tire sizes to choose from. Pretty sure 275/60/20 was one of the options. Not sure how close that will be. Just recently did a local friends truck that swapped on some Rebel take-offs.

 

[BlueHemi1500]

If you are using alfaObd to change the speedometer, there is a tire change option that gives you a list of different tire sizes to choose from. Pretty sure 275/60/20 was one of the options. Not sure how close that will be. Just recently did a local friends truck that swapped on some Rebel take-offs.

That is exactly the magic wand I plan to use from the superhero tool belt. I am hoping that it will be just that easy or use the tire size you gave earlier of the stock Rebel tire size and be close. If not then I will play with numbers to find the sweet spot.

BlueHemi1500

 

[BlueHemi1500]

All
Today I changed my tire size using AlphaOBD, my MX+ Code reader, and a cable. I used a GPS program on my phone to check for the speedometer accuracy with the new tires.
My factory tire size was 275/55/R20 and I changed it to 275/60/R20. I purchased the Bridgestone Revo 3 All Terrain tires.
My baseline speedometer check was off by about 3 mph based on the factory tire size but the new tires were installed.
Stopped and pulled off the interstate into a parking lot. I loaded my copy of AlphaOBD on my phone and looked for a tire size that was close to the factory pre-loaded tire sizes in my truck. I found one that was the exact tire size that was mounted, "Goodyear Wrangler SA 275/60/R20"
I selected that tire size and AlphaOBD reported a tire size of 2462 mm. We (my wife and I) made 2-speed check runs, which seemed correct on the interstate, and drove on some secondary roads to see at various speeds. There is a very small margin of error, but one I am willing to accept.
So next week I will verify yet again when I have more time to try different things.

Thank you all for the information I used it all, along with several other videos I had collected over the previous months and other websites in preparation for this week's upgrade in tires.

BlueHemi1500

 

[A-TEAM]

When I put 33" tires on mine with 3.21 gears it threw the ECU way out of whack. It was 4mph off at 70 (read74). The shifting was not great unloaded and terrible loaded up towing a camper. Got it dialed in perfect with JScan and it resolved all the issues with my setup. I would recommended reprogramming the correct size tires based on my experience.

 

[BlueHemi1500]

When I put 33" tires on mine with 3.21 gears it threw the ECU way out of whack. It was 4mph off at 70 (read74). The shifting was not great unloaded and terrible loaded up towing a camper. Got it dialed in perfect with JScan and it resolved all the issues with my setup. I would recommended reprogramming the correct size tires based on my experience.

I did the same thing using my AlphaOBD system, I was able to find a preloaded tire size that was the exact tire size I had installed, there is a very small error but I am willing to deal with that error it is a fraction of an MPH wrong. It keeps me very close to GPS vs. Speedometer indicated speeds and the factor of error may be a delay in data transfer speed from GPS to phone display vs. no known data lag on the speedometer.

BlueHemi1500