stirling10Fx4

Today I finally had my new tires installed. I went with Mickey Thompson Baja STZ's 275/60/20. Tires went on with ease and balanced out nicely with minimal oz added.
On my trip to my better halfs place, I noticed the transmission hunting a little for the right gear at highway speeds. Took it easy cruising at about 110-115 kmph most of the way. Normally on the inclines where my truck would never downshift to maintain speed, my truck is now downshifting. Around town at city speeds I am also noticing it hunting from time to time trying to figure out the correct gear.
Is it necessary to disconnect the battery and start a new learning curve for the transmission with such a minimal tire size increase?
Also, already have seen a decline in the fuel economy on my first short trip. Looks like a programmer will be on my wishlist for Santa to deliver. Open to any programmer suggestions to get my mpg back to bearable levels as I have not even sunk my foot into her yet.

Thanks in advance.

dieselhunter44

I would disconnect the battery for about 30 minutes then reconnect, so the transmission will learn to shift with the new tires. Also since you went with some aggressive offroad tires you will take about a 2-3mpg hit. Not much will bring it back to stock numbers. It's the nature of the beast.

Snowflake

I've seen guys lose 100+ kms a tank putting aggressive on keeping stock size.

eye.surgeon

I suspect what you're noticing is the effect larger and heavier tires have on power. I doubt if unplugging your battery is going to make any difference. I also doubt if a tuner will be able to reverse the laws of physics and restore your fuel economy. There's a price to be paid for bigger heavy tires.

Bosro

If you want fuel economy do not put bigger aggressive tires on or a lift...
Been there....went back to stock size

gDMJoe

Suspect it's the combination of ...

• speed being off by 3+%
• MUCH heavier tire

Truck owner

Modifications from Stock cost a lot more than the Mods themselves. Lift kits, Bigger aggressive tread tires, shocks,etc..will change the overall operation of your truck. As they say you got to pay to play!! I sure it looks good though..

vmpv

I'm kind of siding with the OP about the battery pull though. I have recently begun noticing something similar to what the OP said. My case will be at low speed so far I've noticed. I'll go into a coast (approx 40kmh) and when re-applying the gas it "sometimes" clunks into the next gear rather than a smooth exchange. I have recently swapped my 20's for 17 winters so I wonder if a re-learn is warranted?
BTW 13 XLT 4x4 SuperCrew approx 22k

svt2205

Disconnecting the battery no longer clears all of the adaptive learned settings. There are now capacitors in the system which maintain power to those portions of the CPU memory.


I believe this video will give you the info you need on how to clear/reset the adaptive portion of the system.

stirling10Fx4

Thanks to all of you who took the time to reply. Even with the slight mpg loss with the addition of the new tires, I am loving the STZ's! Not a whole lot of miles on them yet but some ice and light snow conditions over the past two days have given me comfort I made the right decision with these tires. In conditions where my old Pirrelli hockey pucks would have forced me to use the 4x4 switch, my truck is now pulling through with limited or no wheel slip. Don't get me wrong, these are not an ice and snow tire in any way but so far are performing very well. They have also completely changed the look of my truck, for the better in my opinion. I will try to post some picks of these tires mounted in the next day or two.