[2014BlackSport]

hey guys, i just bought new winter tires for my ram. my stock tires are 275/60/r20 and the new winters are 275/65/r17. so almost a 2 inch difference. will this damage or effect anything other then my speedo? and also i heard the speed runs off the diff so will it even effect it at all?thanks guys

 

[SK-Ram]

Your speedo will be off causing shift points to be off a well. Just make a trip to the dealer and have them correct it, that is if you don't have a tuner.

 

[2014BlackSport]

i do not have a tuner. so i will have to go then. but it won't effect my diffs or tranny in a negative way? thanks

 

[SK-Ram]

Not if you get the speedo corrected. My Ram came with a 265/70/17 tire stock, they will adjust your speedo to that size and that'll be pretty well spot on. I went from that 265/70/17 to 35/12.50/17 without adjusting anything for 24,000kms and my speedo was out about 10%, tranny and diff are fine. But it really should be corrected to get your shift points corrected and have the speedo accurate.

 

[2014BlackSport]

awesome thank you

 

[Rambunkshuss]

It doesnt effect shift points, the shift points are programmed into the TCM. Smaller diameter tires wont effect the truck much at all, you`ll just be going slower than what the speedo actually says. I have a sport with OEM 20`s, i switch them to 265/70/17`s in the wintertime, speedo is only (approx) 4mph off. Waste of time messing with the speedometer in my opinion... then have to change it again in the springtime when you switch back to your 20`s. Just drive it and dont worry about it.

 

[Ranman]

It doesnt effect shift points, the shift points are programmed into the TCM. Smaller diameter tires wont effect the truck much at all, you`ll just be going slower than what the speedo actually says. I have a sport with OEM 20`s, i switch them to 265/70/17`s in the wintertime, speedo is only (approx) 4mph off. Waste of time messing with the speedometer in my opinion... then have to change it again in the springtime when you switch back to your 20`s. Just drive it and dont worry about it.

X2^^ No need to go to the dealer. Yes the speedo will be off a bit but don't worry about it. Especially if your planning on running factory 20's in the summer.

 

[sport654]

The closets size tire to a 275/60R20 tire in 17" rims is 255/80R17 which represents only a .21 difference (overall height & width). In other words the 275/60R20 are .07 inches smaller in circumference than the 255/80R17's. This would calculate to a .2% difference in your speedometer, so you can switch between seasons with no adjustment needed. It might be worth trying to exchange if you haven't already used your snows.

 

[MudEngineer]

hey guys, i just bought new winter tires for my ram. my stock tires are 275/60/r20 and the new winters are 275/65/r17. so almost a 2 inch difference. will this damage or effect anything other then my speedo? and also i heard the speed runs off the diff so will it even effect it at all?thanks guys

If you wanted the tires to be nearly the same diameter, you should have bought 275/75/R17 which would be 33.2 inch diameter compared to the 20 inch being 33.0 inch diameter. Speedo would be off by less than 1%. You will be off by almost 6% with the tires that you bought (31.1 inch diameter), but you should have more apparent power as you effectively changed the gear ratio by 6%. It is like going from 3.21 gears to 3.40 gears. Gas mileage will suffer some. If it used to be 10 miles to drive to work, it will now show 10.6 miles on the odometer. 70 mph on the speedo will only be an actual 66 mph.

 

[92896]

borrow a gps and see how much your speedo is off. That will help you gauge your speed for the winter to avoid tickets.

 

[Rambunkshuss]

Way more thinking going into this than necessary, just drive it. If you`re going slower than the speedometer says, you certainly are not going to get any tickets. Untrue about mpg`s being worse, mine remained the same due to driving a little slower. You actually end up with less miles on the odometer as well, with smaller diameter tires.

 

[Bob Chapman]

I must be missing something. Why did you buy 17" winter tires when you could have bought 20" and had them mounted on your existing wheels?