1997 Dodge Ram 1500 4WD 5.9, Changed tire size from 265 to 315.
Gas miliage with 265 tires, was 15 MPG.
Changed out front/rear ratios from 3:55 to 4:10, hopefully to make up for larger 315 tire size and calibrated Speed Sensor to match 315 tires.
Installed 315 tires and GM went to 13 MPG.
Installed 3" body lift.
Changed out PCM and for the first 32 miles, GM up to 15.5 MPG.
Reset odometer, refueled after another 32 miles and GM back to 13 MPG.
Found partially blocked CAT and had same as well as muffler changed out to 3" exhaust system.
Reset odometer and refuled after another 32 miles and miliage up to 17 MPG! No, ****!
I'm at a loss as to what has happened other than spending a lot of money and time for nothing.
What did the 3" exhaust have to do with the 17 MPG or the PCM with the 15 MPG?
Truck looks good, but WTF!
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have you replaced any tires lately if tire size is off a little this will happen i dont mean two different sizes if you have new tires on front and worn tires on rear or vise versa on large tires it dont much to change diff ratio so front and rear wont match
first thing to check is are the tyres the standard size, or has it got
thinner profile(the distance from the road to the wheel)tyres fitted.
because i live in England,i dont know what size they should be.but the only other answer is final drive/gearbox ratio changed from new(replacements)please check and get back if i can be of further help.
both tires will fit on the 15 inch rim But be advised make sure you have same size tires on the drive wheels being as your car is front wheel drive u want both the front tires to be the same size if this is not done u will burn up your transmission if you have to put a odd ball tire on put it on the rear
exact opposite is true for rear wheel drive car on a rear wheel drive car u want both rear tires to be the same size
Tire A: 195/65 R 15 (25 x 7.68 x 15)
B: 215/60 R 15 (25 x 8.46 x 15)
Were you not planning on increasing the tire size after lifting it? They may look a little small with a 3" lift, its a personal preference. If it was me, I would probably go to a larger tire like 285/75R15 or even 305/75R15. Also remember if you put a bigger tire on this thing the speedometer will be off. It will say your going 55 but you may be going 60. Also bigger tires will change the overall gear ratio. It will increase gas mileage but lower the torque to the wheels.
on the side of the tire you will see a tire size, it should read something like this 175 55 R15 ms or something like that, look at all the tire sides, all or them if they are the same should have the R then a number like 15 or 16 or 17 etc. that is the rim size, look at the first number and the last one, cause the first will tell you the height, a 165, 155,175,etc. all the numbes on all the tires should be the same unless you have preformance tires on it then the front will be smaller then the back tires.... hope this helps you out.....
You should have the same size tires in the front and back. By having 2
different sizes, you are changing the gear ratios between the front
diff. and rear diff. You could wipe out the t-case especially if it is
full time 4wd.