Tires not matching ('00 Mounty)

[CDW6212R]

Those tires are almost the same diameter/circumference as the factory option 255/70-16 tires. The factory options are about 1/2" wider.

https://www.tacomaworld.com/tirecalc?tires=255-70r16-30-9.5r15

I had some odd shifting issues when I went from 235/75-15 to 255/70-16 tires on my '99 Mounty AWD. After I recalibrated for the larger tire size, it disappeared. I haven't read anyone else post about this problem so maybe it was just me?

Hi Dan, did you use the NGS device to recalibrate your 302 truck? The last I had read suggested that the V8 2nd gen's couldn't be corrected. I've figured it could be done, but hadn't looked hard for an answer.

Did you change the PCM to do that? I've had these 2nd gen's with both 15's and 16's, the 30" tires seem to be the most accurate for the speedometer. I'm planning to end up with 29" tires on both of my SUV's, so I might like to tweak the speedometer a hair to speed it up.

 

[intelisevil]

On '97 and earlier you can change out a little plastic gear to correct the speedometer.

On '98 and later (not sure how late, but definitely 2nd Gens) you need to tweak the computer. The NGS device is the way Ford service departments do it if you can talk them into it.

I went to my local Ford dealership to get my speedometer recalibrated, great Parts people, not so good Service! I was quoted "about $300 because we can't do it here, we have to send it out". With that I figured I could do the math on my own and use my GPS.

Starting the day I put the larger tires on I had some odd shifting in town. After about a week of this I disconnected the battery overnight, hoping to cause the computer to relearn with the new tires. After no luck on this experiment I found an NGS device on eBay for slightly more than Ford's quote. 10 minutes after unpacking the NGS I had my computer adjusted and shifting was back to normal.

 

[CDW6212R]

Very good Dan, I'll make plans to get mine worked on when needed.

BTW, the Explorers had the speedometer gear and sensor removed in 1998, when they included it in the rear end with the ABS sensor.