I have a 2002 f150 v8, it has a lift with 35'' nitto mud grappers. I want some more get up and go so i was thinking of regearing to 4:10. but i might also in the future upgrade to 37/38's. Will it be ok to go ahead and get the 4:10's even if i do deside to get the 38's later? or should i go ahead and get 4:56's for the 38's?

 

You are a little off! You should be looking at 4.56 for 35s, or 4.88s for 37s.

 

3.73 are perfect for 35" Tires. What motor do you have? get a programmer It'll work wonders you really don't need to re gear your truck with gust 35" tires

 

My truck came from the factory with 3.73s and 32" tires, so I would hardly say that it is perfect with 35s! A programmer helps but the engine and transmission definitely have to work harder, especially towing and driving in the mountains. I felt like 3.73s and 35s were "okay" with the truck under a lot of circumstances as long as I was on fairly flat terrain. After re-gearing there is no comparison, the truck feels 10x better and there is a lot less downshifting, as well as a lot less slippage in the torque converter.

 

im runnin 4.88s on my 35s
its great and towing night and day from my 3.73s

 

i have the 4.6 v8 bigtrouble and the other reason i want new gears is cause i already blew a pion seal and my rear diff has leaked since i got the tires
mav, hows the pick up on the 4:88's?

 

so i guess the question is now, 4:56 or 4:88's? lol

 

uummm., no. but the programmer does help!

uummm, exacty.

you got it. ^ go with his advise. 4.56 with 35 and 4.88 with 37/38's. you cant find a better answer.

 

the pick up on the 4.88's is great
i like the pick up off the line alot but im only on 35 will be on 37's soon dont have te money and fresh rubber now so ima wait

 

Well I guess I'm the only one that knows that the taller the tires makes a difference in the gears that are all ready in the truck. I have Looked into it. heres a chart to show exactly the best gears for towing, fuel mileage, and more power depending on what you want to do. I requmind staying close to the factory gears as possible.



Gear Ratio & Tire Size Chart

Good "rule of thumb" calculation is to mutiply .12 by your tire diameter. (.12 X 38" = 4.56)
(see more formulas at bottom of page)

The below table can be used to get a rough idea on gear ratios. The colors represent ideal RPM's at highway speeds (65). For highway cruising and best fuel economy stay towards the yellow (2600 rpm), around town daily driving is color coded green (2800 rpm), and for better towing power or just more 4-low power use the ratios near the red (3100 rpm). These calculations are assuming a manual transmission with a 1:1 ratio. If you drive an automatic your RPMs will be slightly higher, and the opposite is true if you have overdrive (your RPMs will be slightly lower).

Better Gas Mileage Near Factory Ratio More Power

Gear Ratio
T
i
r
e


D
i
a
m
e
t
e
r

3.31 3.42 3.55 3.73 3.91 4.11 4.27 4.56 4.88 5.13 5.29 5.38 5.71 6.17 7.17
27" 2677 2766 2872 3017 3163 3325 3454 3689 3947 4150 4279 4352 4619 4991 5800
28" 2582 2668 2769 2909 3050 3206 3331 3557 3806 4001 4126 4196 4454 4813 5593
29" 2493 2576 2674 2809 2945 3095 3216 3434 3675 3863 3984 4052 4300 4647 5400
30" 2410 2490 2584 2715 2846 2992 3109 3320 3553 3735 3851 3917 4157 4492 5220
31" 2332 2409 2501 2628 2755 2896 3008 3213 3838 3614 3727 3790 4023 4347 5051
32" 2259 2334 2423 2546 2696 2805 2914 3112 3331 3501 3610 3672 3897 4211 4894
33" 2191 2263 2349 2469 2588 2720 2826 3018 3230 3395 3501 3561 3779 4093 4745
34" 2126 2197 2280 2396 2512 2640 2743 2929 3135 3295 3398 3456 3668 3963 4606
35" 2065 2134 2215 2328 2440 2565 2664 2845 3045 3201 3301 3357 3563 3850 4474
36" 2008 2075 2154 2263 2372 2493 2590 2766 2961 3112 3209 3264 3464 3743 4350
37" 1954 2019 2095 2203 2308 2426 2520 2692 2881 3028 3123 3176 3370 3642 4243
38" 1902 1966 2040 2144 2247 2362 2454 2621 2805 2948 3040 3092 3282 3546 4121
39" 1854 1915 1988 2089 2190 2302 2391 2554 2733 2873 2962 3013 3198 3455 4015
40" 1807 1867 1938 2037 2135 2244 2331 2490 2664 2801 2888 2937 3118 3369 3915
41" 1763 1822 1891 1987 2083 2189 2275 2429 2599 2733 2818 2866 3042 3287 3819
42" 1721 1778 1846 1940 2033 2137 2220 2371 2538 2668 2751 2798 2969 3208 3728
43" 1681 1737 1803 1894 1986 2087 2169 2316 2479 2606 2687 2733 2900 3134 3642
44" 1643 1698 1762 1851 1941 2040 2119 2263 2422 2546 2626 2670 2834 3063 3559

Common gear formulas:

Gear Ratio

Crawl Ratio

P-Metric to Inch Diameter

Tire Change (find new gear ratio)

Speedometer Adjuster (with oversize tires)
(New Tire Diameter / Old Tire Diameter) * Speedometer MPH = Actual MPH

Simple Gear Ratio Formula
Ring Gear Teeth Count / Pinion Gear Teeth = Gear Ratio

 

oh the website that i found this chart at is 4Lo.com

 

ight thnx guys

 

What? lol
Yes, you must be the only person in the world who knows this.

The chart you posted would only work for the F150 in 3rd gear for "somewhat" accurate RPMs. Also, every engine is different and works better in different power bands, so the recommendations on that chart don't mean anything.

Maybe you don't know this, but when you run significantly larger tires, you are increasing the rolling resistance, rolling mass, wind drag from the tire, and also generally even more wind drag from a taller overall vehicle profile. Therefor, re-gearing to keep the overall ratio as close to stock isn't normally the best approach. The bigger and heavier tire is going to take more power to get it turning. You should gear lower (higher numerically) to help compensate for that. I for one wouldn't be spending a bunch of money to re-gear and still have "worse than stock" performance.

Here is a very basic calculator to determine what gears would bring the truck back to stock, and suggest higher or lower, when changing tire sizes.
http://www.therangerstation.com/tech...tioChange.html

For even more in depth gear calculators, look here.
http://www.angelfire.com/fl/procrastination/rear.html

 

With 35's you need 4:56, but I would go with 4:88's cuz you got the 4.6. Now here is my truck with 4:56's and 35's. That will put you back to "stock" RPM's. Now with 37's or 38's you need 4:88's, and thats going to put you back to the RPM's your truck was turning with stock tires.
And this pic is in OD, 3rd at 65mph is turning 2800 RPM's.

Hope this helps....

 

yes you said what i was thinking but if you dont mind i would like to say it in my own words.




well, where should i start. lets go with what brian said first. the chart is saying your in drive, not overdrive for one. those charts tell you rpm in 3rd (like he said) and only gives you an rpm of what mph your driving. it doesnt account for heavier tires, taller wind resistance and overall heavier rolling resistance.

second, im glad you (big trouble) can read these charts. they tell you what rpm your cruising at a certain speed. what they dont tell you is the acceleration difference with heavier and taller tires. if i wanted a good cruiser at rpm i would have stuck to my 3.55 gears according to your chart.

what your forgeting is your talking to people that have real world seat of the pants experience who love their change in gears and feel the accelation they get from the added gear ratio. what your missing is real world driving. real people experience. common opinion of what some have done and whether they like or hate the difference. not what a chart said. thats the advice i take from this site.

i pesonnally changed mine to accomodate the taller tires and what that brings for accelarating and towing! why dont you show me that chart? now that you mention it my rpm's at 70 is 2050 in overdrive. by far not a bad place to be.

as far as you are the only one knowing this, can you please edjucate us in how gears help getting us moving, not just at a certain speed. that would impress me since you know "the good rule of thumb".

a little MGD 1.0 version there.