How many of you had gears installed after lift and oversize tires?

[mad103]

Just was informed that it is advisable that I have new gears installed into my 05 because of the oversize tires. I am running 38s. This is new info for me so just wanted to see how many of you have done so, as I know many with a lift and stock gears running their truck ok

[GregsSD]

If you don't tow heavy loads and are OK with the power that you have now then you don't need to change your gears.
But if you want your towing power and all around power back like you had with smaller tires then you will need to go with lower gearing to offset the tire size.

[scottf4444]

I tow and didn't want to worry about the tranny. I re-geared to 4.56 when I put 37" tires on. Probably personal preference.

[Jacked05Powerstroke]

I still have stock gears in my 05 and I am also running 38's. I have an off topic question...how wide are your tires? 13.50's, 15.50's?

[mad103]

^yea most people I know with lifts keep stock gears. I am running 15.5 I believe. My truck aint here so cant double check

[hypersnyper694788]

I think its rough on the transmission to have the stock gearing with the bigger tires and it kills your tq. Im happy with my 3.73'ss with my 35's but if I go back to 37's im gonna do 4.10's or 4.56's

i got 35s on my 2000 and i hate how much it pulls the power down, gonna either swap to smaller tires or regear

[RescueF250]

Remember alot of folks try to compare tire size and gear match with gasser trucks they are no where near the same. Im running 4.30's in my truck and they are great on the highway and pull the truck really well. Any upgrade in gears will help your truck period. Yes 4.56's is nice for towing but you gonna be in a higher RPM burning a little more fuel. IF you plan to tow alot 4.56's, if not get yourself 4.30's and you'll be fine. Im running Toyo 38x15.50R18 MT at 75mph im at 2100 rpms which is just about stock. That should explain enough. IF you go with a higher gear only problem with that also is if you decided to down size your tire, your screwed to a certain point.

4.30's is my vote.

4.10's 35 to 37 depending on true tire height.
4.30's 37 to 38 depending on true tire height.
4.56's 38 to 40
4.88's 40 n above

[topdwg]

This is also a prett good calculator that will help determine which size gear to go with.

Randy's Ring & Pinion. RPM Calculator.

[RescueF250]

I wouldnt follow that if I were you I put my set-up in there and it gave me 2900rpms. When Im running 2000 or 2100. Its not set-up for a diesel truck, even though it give you a break on on the side.