275/60/20 vs 275/55/20 tire size

[Frankwhoa]

How many of you have dropped down to a 275/55/20?

I just bought a set of take offs with 14 miles on them from a 2019 1500 Laramie for a bargain.

What is the best way to update speedo and tranny or does it matter with that little size difference?

Should I let a tire shop or the dealer do it?

Almost forgot, I will also need to relearn the tpms... best way for that also?

Thanks guys

 

[CincyCuda68]

AlphaODB is the best value for programming a lot of functions on your truck, tire size and tons are just a couple. That being said, not sure that little difference would make you too far off. I went from stock tires to 35x12.5 and the difference was about 2-3 mph.

 

[Frankwhoa]

AlphaODB is the best value for programming a lot of functions on your truck, tire size and tons are just a couple. That being said, not sure that little difference would make you too far off. I went from stock tires to 35x12.5 and the difference was about 2-3 mph.

Thanks, what about shift points and performance from using a smaller tire?

 

[CincyCuda68]

Thanks, what about shift points and performance?

I have the 6.4 Hemi from what I understand there isn’t a whole lot you can do with a gasser but that would require a tuner if it’s 2018 you have to get an unlocked pcm to use the tuners.

Alpha thread here. Tons of info on what you can do.

https://www.ramforum.com/threads/alfaobd.123982/

 

[Bigskyroadglide]

I ran a set on my 11 Eagle GTs for about 50 k. Speedo was off 3 mph.

Hated how they drove.

Maybe it's because they were 55s

Never again

 

[Fatbob Frank]

I did the opposite.
Went from 275/55-20s to 275/60-20s.
No tune or reprogramed speedo.
I notice on the 'check your speed' radar signs they have around town that I'm about 1mph fast @ 35 and 2mph fast @60.
Not enough to spend the money on a programmer IMO...

 

[cityboy21]

https://tiresize.com/calculator/

tells you all you need to know and then some

 

[BWL]

275 60r20 is an available stock size so you may be able to get the dealer to change it if you go in for any recalls that involve plugging it in to flash it for minimal or no charge.

 

[grizzstang]

You can use an AEV Procal to adjust your tire size.

It also does a few other things and does not require you to get an unlocked PCM.

I used one on my 2017 for tire size adjustment and it works great.

Make sure you get the right one. One is for Rams 2013-2017 and one is just for the 2018.

https://www.aev-conversions.com/product/ram-procal/#year