Wheel & Tire Question

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TommyR

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Aug 29, 2021
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2015
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5.7 Hemi
Hi,

I just picked up a new to me 2015 5.7 Ram 1500 (6 speed, 3.55). The build sheet indicates that the truck came with the stock 265 70 17s (that's what the spare underneath is). The previous owner put 275 60 20s on it with stock 20s. The speedo is off a bit due to the bigger tires on it (4.4% difference in tire diameter). I did quite a lot of reading/searching to get to this point and didn't find all of the info that I was looking for so my questions are as follows:

-Will the upsized tires (33" vs 31.6") have any negative effects? (e.g., changing transmission shift points/harder on transmission, altering ABS etc)
-Do people regularly switch over between stock 20s and stock 17s in the winter with no ill effects and no speedo recalibration?
-If I were to blow a 20" tire and have to use the factory 17" spare would that cause issues?
-Would I be better to run a 275 55 20 which is much closer to the size of the factory 17 (31.9" vs 31.6") and if so could I still use the spare if needed?

Thanks in advance for any help. It is my first truck so I'm just trying to figure out what is best to do.

Tom
 

Dean2

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Welcome to the Forum, good to see another Canadian. People put on 20's cause they think they look cool. Personally, I am not fond of the high cost of 20" rubber so I run 16 and 18. Also, the selection of off road tires is much better in the smaller sizes. As far as the taller tire, it will not make enough difference to be any problem. If you get a flat on the rear, just don't run on the spare very far. If you have no choice put a front on the back flat and the smaller tire on the front. In 2 wheel drive it will make no difference on the front. Final thing, the dealer can correct the speedo for you so it is back dead on with the larger tire in place. All the best.
 
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JohnCA

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If you want to keep running with the larger tires you could get a 255/80R17 for your spare, as for the effect of larger tires, you do lose power both from the additional rotational mass and the less RPM your engine turns to achieve the same driven speed.
 

kurek

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Got an Android device (tablet/phone) ? Get an OBD2 dongle and download JSCAN, spend the $22(US) on a license for JSCAN and update your speedometer. That'll get your transmission shifting at the right time, save you a little fuel mileage and keep your speedometer accurate. It's easy, takes 90 seconds.
 
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TommyR

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2015
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Thanks for all of the advice. I really appreciate it. Always nice to see another Canadian on the forum as well Dean. Thanks for the upsized spare advice as well JohnCA and finally I will look into JSCAN as well. All of you have been a great help and given me some things to consider.
 
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