Tire size and speedo change/shift points

[NonHyphenated American]

Has anyone went from 245/75/17 to 255/75/17 and not reprogram for tire size? I had a JL and went from 245 to 255 and the speedometer was dead on. It was a 6spd so obviously I didnt have to worry about shift points. Anyone do the same upgrade and have any problems with the speedometer and shift points? I cant remember where I read it, but the JL can relearn the new tire size and adjust according. I assume it would be the same on the Gladiator?

Im trying to decide on what tire size to buy. My choices are Kenda Klever MT in 33x10.5x17, General ATX in 275/70/17, and Falken Wildpeak MT in 255/75/17 or Firestone MT2 (Willys take off)in the same size. Kind of shying away from the Klever because they are such an odd size for being readily available. I would go 285/70/17 if I found a good deal on Rubicon or Mojave take offs. I figure the 255s wont upset the dealer because they are the same size that come on the Willys.

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[Free2roam]

I went from stock Sport S Ecodiesel 245/70/17 tires to 275/70/17 dealer said there was no need for reprogramming. Didn't notice any difference. Upset the dealer? My dealer put them on for me. Bought them off another forum member.

 

[NonHyphenated American]

I went from stock Sport S Ecodiesel 245/70/17 tires to 275/70/17 dealer said there was no need for reprogramming. Didn't notice any difference. Upset the dealer? My dealer put them on for me. Bought them off another forum member.

I havent had any issues with past Jeeps and mods with my local dealer. There might be that one day I get a dbag service manager.

 

[Shopshirt]

I swapped over to Rubicon wheels and Tires, which are 285/70R17 = 32.7x11.2R17. I haven't noticed any change in shift points, however, around 65-70 the speedo reads about 1 mph slower than Google maps GPS speed. So 70 = 71 mph actual.

 

[1996XJ]

So today i switched from the 32 inch stock duelers on my Sport S to Falken 33 inch mojave take offs. The speedo seems accurate, i went to my dealer which was a joke. A child had to ask another guy if i should flash the PCM for the new tires and he said they dont have the tool to do that. That is strange because they are reporgramming the Mojave PCM because of a recall Tuesday. Then when i asked if the change will effect my shift points the guy says maybe i should go get it regeared... i said when i switch to 35s or 37s i will regear it and who can i email at jeep to get a price for a regear to 4.88s. He tells me they dont do that because its not factory specs... Long story short ill take my free oil changes but probably wont be getting work dont there. Still wondering if the tire change will really change much on how the Sport shifts. So far it seems to drive fine just a small loss in pep but i think thats due to the larger footprint on my wider tires. The pizza cutters actually peeled out a little.

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