Advise Needed here about 4cyl.

Hey guys...I'm going to make this short and simple...

My truck is a 2017 4cyl a/t, scab, it came with 4.30 gears and 245/75R16.
I'm currently running 255/70r17...but I've been thinking about going with 275/70R17 .
According to the chart, it brings it more into the "factory" range...

What impact would it have on my rear dif. gear?
Mpg's?


Any help would be appreciated... thanks

 

Which chart are you referring to?

The tires won't make a difference on the rear diff but you'll likely see a loss in mpg

@Diablo169 has the 4 banger and larger tires.

 

This are snapshots... first two for the 255's and last two pics for the 275's...

 

you have to look at the weight of the tires and also the contact patch width(tread width)you ideally want a thin tire that's less road contact and less rubber the engine has to push, these are crucial when dealing with a 4 cylinder 2.7l

 

I have considered that also... light (somewhat) tires nothing crazy like KO2's.

 

its a very tough decision if you own a 4 cylinder but want to retain the little stock performance but want a better looking tire/wheel setup. im going thru this with my truck its a daily driver and don't want to sacrifice looks for performance. most of the lightweight all season tires in 245 size have low ratings and reviews, only the heavier sized 245's are having better consumer ratings, every extra pound of tire weight over stock 32lbs. translates to 10 more pounds of unsprung weight the little engine has to push.

 

Ah ok, I see now, so while that information is good, you need to take them with a grain of salt. I say that because their calculator is based on 1:1 drive ratio in 4th gear and I don't know about you but I don't drive around in 4th gear. A lot of the gear calculators originated from the Jeep world. A significant number of people were swapping Jeep transmissions like the BA10, AX5 and such for GM truck manual transmissions like the SM465 which is a 4 speed and the highest gear was 1:1. Almost every 5 speed transmission Jeep used with the exception of maybe the AX15 was terrible which is why everyone dumped them for 4 speeds for offroading. People needed to know what their RPMs would be curising the highway in 4th gear. Everything became slightly skewed when new ATs were released with OD gears and more so now with 6 and 10 speeds transmissions and so on.

At 65 mph your truck should be in 6th so lets calculate the difference.

4.3 axle ratio * 0.58 Trans ratio = 2.49 final drive ratio.

@65mph on a stock 30.5" tire your rpms will be 1786
@65mph on the new 32.2" tire your rpms will be 1692

Compared to the 3.5L Engine

@65mph on stock 30.5 your rpms would be 1620
@65mph on new 32.2 your rpms would be 1534

Overall you are geared lower than the stock 3.5L trucks and thus have a little better drive ratio for larger tires. What impact that will have on the 4 banger I dont know. I assume you will burn slightly more gas and maybe see a 1 mpg drop.

 

Wow...
I thank you for your time @JoeCOVA.