i have a 96 bronco with the 5.0 5 speed and 60k on the clock. i will need new tires this spring and i am somewhat interested in putting on smaller tires, ok dont shoot me hear me out. now i have 31-10.5" on my truck and it is a dog in the mountains. i rarely go 4 wheelin except for camping and fishing. a lot of the time i am hauling 5 people and snowboarding gear up 14,000 ft mountin passes and the bronk is a bit of a dog. i was wondering if i were to make the switch back to stock 235/75/15's or maybe 30-9.50's would that make much of a difference. i have done the math and my speedo with the 31's is about 7% off. any suggestions would be greatly appriciated. i also plan on pulling a snowmobile trailer next year and would like to know if getting a little gear back would help...

thanks guys!

 

first of all, 31 x 10.50 is probably stock on a 96, i thought they were stock on all 88 and newer trucks. the sticker inside of your door will tell the tail. As per the high altitudes, i woudl think your mass air truck should be better at compensating, but you may want to think about a chip, that will richen up and control your timing a little more to make a little more power. When its being a 'dog', does it start pinging? I would check your timing and plugs/wires/cap/rotor, in addition to possibly running a higher grade gas. at 60k, the bronco jus tmigh twant a good tune up. If that doesnt help, the smaller 30 x 9.5 tires will get ur revs up just a little more to give you a bit more pep, and may be a nice difference to ur power and still maintain off road capability, or the 235's even more so, remembering that your rpms will be higher to make that power and may effect fuel economy. I imagine that you have 3.55 gears, if not you might want to consider upgrading to 3.55 gear sets out of another bronco, or if you have 3.55's possibly upgrading to 3.73;s would give you more power too, instead of changing tire size.

 

The door sticker says that 235/75/15 is the factory size. there is no pinging under load so i feel that the timing is set right.

i know all of the 5.0 mustang guys run their timing at like 12-13 advanced to get more power. would this work on a bronco, not being a H.O and all?

 

my 96 did not come stock with 31s, i had to buy em off an older bronco to make it some what trail worthy.
it didn't seem 2 be fast with the stock tires as apose to the A/T 31s but man those 31s would smoke like nothing

 

stick with the 31's and just install a k&n filter up the timing to 12* and run 89 octane, you might also concider getting some headers and a nice exhaust system. this will help a lot. Before i swapped my 302 for a 351 i added headers and a single 3" exhaust with flowmaster an the throttle response and traveling high alt was no problem.

later

 

My friend has a '93 5.8 just like mine with 32's on all four corners and he averages 14-16 miles per gallon. My rig with 30X9.50 will not get more than 12 miles per gallon no matter the average speed in city or highway..