Newbe Help with tire size

[Da-rider]

I read on a back posting about putting big tires on a ranger to get better economy lowering rpm's. Hannsb2 gave a very good answer about low rpm's and lugging the engine, well now that I put 265-75R-16 Goodyear Wrangler on my Ranger economy went down. So I am probably lugging the motor? I have a 4.0-4.10 gears-auto so I thought bigger tires lower rpm's better economy. Now do I chip the motor and if so which chip to run? I don't want to re-gear. I don't do any heavy 4 wheeling just two track and dashin through the snow. It's a daily driver. Being that I'm a newbe any help will be greatly appreciate.

 

[4x4junkie]

Not a whole lot you can do other than regear or swap to smaller tires.

4.10s and 265s (31s, basically) shouldn't be a bad combo with a 4.0L though. What pressure are you running? Maybe up the pressure some.

 

[Da-rider]

When tires were mounted they set them at 32 psi then I went to 35 psi now 40. I believe max is 45 psi but do not want to run that high. I thought chipping it would change shift points and up the horsepower and possibly up the gas economy that's why I was open for suggestions.

 

[4x4junkie]

No that would likely only make the engine work harder, consuming even more fuel. The engine is generally most efficient at whatever RPM the torque peak is at (this is primarily dictated by the shape and size of both the intake plenum, and exhaust).

Are you compensating for the fact your speedometer now reads slower with the bigger tires when you are figuring your mileage? (or have you had it recalibrated)?

 

[Da-rider]

First off thanks for the help. I checked the speedo with the gps when I first had the tires mounted about 2.5 to 3 mph faster. Took for a ride today after reading your thread and I went 10.7 miles on the odometer and the gps said 10.8 now I don't know if that will increase the more miles you go. Guess I will have to check when I take a longer trip.