How much size difference can I get away with?-street tires/offroad tires

mando jake · #1 (**permalink**) 06-26-2009, 11:33 PM

I'm thinking about running 33-35 inch tires on street, and keeping a set of 40-44-? inch tires for mudding, playing etc... Is anyone else doing similar? Am I just asking for too much versatility? What do you think would be the biggest tires to swap out for 33-35's for this purpose? And, what kind of lift are you guys needing to run said tires?

A little background information:
88 F250 EFI 460 ZF5 3.55 gears limited slip. I have a 91 D60 front w/limited slip, will be rotating C's for pinion angle before installing. Will get a 203/205 double T case in the fall. Currently looking for V code SD front springs, and some long Cheby rear springs. Lift will be entirely springs/drop brackets, no blocks, no shackle flip. I will be cutting out the fenders for clearance instead of a huge lift....for now.

Blue Rebel · #2 (**permalink**) 06-27-2009, 07:02 AM

Heres my truck on its 33" street tires:

And here it is on its 38" Swampers:

Only lift is from a 4" suspension lift from Rough Country

Prozon · #3 (**permalink**) 06-27-2009, 04:35 PM

I could never really see the point in swapping out tires. If anything i'd get something else to drive as my daily driver. (Which I did.) I was running 37's on the street for awhile as my daily driver.

Blue Rebel, have you ever thought to invest in a couple cans of spray paint? They're like a dollar each from Wal-Mart. Might make the truck look a little better.

master_mechanic · #4 (**permalink**) 06-27-2009, 05:08 PM

I think you'll have some power problems running 40's or 44's with 3.55 gears... and if you did regear to somthing like a 4.56 to 5.38 to run the 44's you going to be at some high rpms running on 33's

mando jake · #5 (**permalink**) 06-27-2009, 06:24 PM

I think you'll have some power problems running 40's or 44's with 3.55 gears... and if you did regear to somthing like a 4.56 to 5.38 to run the 44's you going to be at some high rpms running on 33's

That's what the doubler case will be for. Basically, it will have a shift position for big tires. I'll prolly be taking off in 2nd gear, when the doubler is in ~4:1. I'm trying to build a very versitile truck.

master_mechanic · #6 (**permalink**) 06-27-2009, 07:51 PM

so your going to drive it to where your going to wheel it then swap out the tires?? or just drive around in low range with the big tires?

mando jake · #7 (**permalink**) 06-27-2009, 10:15 PM

I'm going to use it to work with, and maybe once a month it will see a trail or mud race or truck pull or tree stump or.............
If I go trailing it will be about 15 miles away and I'll just drive in low with the bign's.

My question pertains more to steering and lift geometry than gearing. I don't want to have a huge lift with little 33's, but I also don't want to have huge tires rubbing the body and no room to flex. I'm thinking about the boomerang or banana style shackles for some droop/flex, but have not decided.

hav24wheel · #8 (**permalink**) 06-29-2009, 11:08 AM

11 inches total lift to fit 44s. That's without trimming the TOP of the wheel well opening. The front and rear of it is trimmed a lot. Also gearing is a huge thing to think about. I'm running 5.38s in the axles, C6 trans and a doubler. I run it in low low(both 203 and 205 in low) more that I thougt I would off road. I'll run with just the 205 in low in the snow and some mud. But it still dogs out some times(in just low) Yes your 5 speed will help a bit, but not enough to keep the 3.50s in the axles with a 40-44 inch tire.

mando jake · #9 (**permalink**) 06-29-2009, 05:35 PM

Ok, correct me if I'm wrong, but having a doubler in lo lo with 3.55's would be the same scenerio as having a single T case in lo with 7.1 gears. Right?
single np205 ~2:1
203/205 doubler~ 4:1

hav24wheel · #10 (**permalink**) 06-29-2009, 05:47 PM

Yes your math is correct. I'm just letting you know from my experiance, it you plan on wheeling in mud or entering truck pulls, lower gears are better. Run the 3.55s and if you don't like it get lower gears later on.

Blue Rebel · #11 (**permalink**) 06-29-2009, 05:55 PM

I would consider putting 4:10s or 4:56s in to run the 33s, and that will also then help w/ the doubler. I have 4:10s in my truck

and im not gonna waste the 200 dollars in spray paint to get it to look good that way, when i plan on painting it all again soon as im finished w/ the body swap anyways. just waiting to find a rust free core support and im good to go.

mando jake · #12 (**permalink**) 06-29-2009, 06:27 PM

Well, I understand that the lower gears perform better offroad. I would only be offroad a couple times a month playing. Most usually just working or hauling. My ultimate goal is decent fuel economy and decent offroad performance, and excellent durability from one truck.
I'd love to be able to have a truck devoted to playing, but knowing how I am, it would have to be a tank also, or I would be working on it more that I would get to play. It's just like an airplane ride: It only costs twice as much to ride first class.

I don't have to have the best mudder/puller/crawler in town, but I'm trying to build smart so I can get the best I can in all areas, out of what I have.

I originally wanted 3.73's front and rear, but had a hard time finding what I wanted for almost free, like I can afford. So, I'm gonna go with the math for now and try 3.55's (cheap, easier to find). I've found a great deal on a set of 40" tires, but I know I want 44"+ for playing.

Prozon · #13 (**permalink**) 06-29-2009, 06:31 PM

I'm running 4.10's and they worked well for the 33's and 37's

82F100SWB · #14 (**permalink**) 06-29-2009, 07:02 PM

A buddy of mine is running a Vortec 350/TH350/203/205 in his Toyota with 4.10's and 44's, and while it does work pretty decently in low/low, he really wishes he had 5.13's. Another friend of ours runs the same setup with 5.13's in his S10, and the difference in power is amazing.

75F350 · #15 (**permalink**) 06-29-2009, 07:10 PM

Double the torque on 3.55 gears with 44" tires equals lots of broken driveshafts.
Gear reduction higher up the driveline, and further away from the wheel is terribly hard on components.
This is a case where the concept sounds good on paper, but s not practical.
Notice that we dont see this combo on any other rigs out there? Its not because it has not been attempted, its because it does not work.
Theory, seems to be sound enough, but in a practical sense it is not.

Now lets consider the mechanics behind the low range splitter, or range box of the 203. Find yourslf running that in low range for extended periods of time, and you will be buzzing the shaft and bearings at an incerdible rpm. These bearings last only when speeds are kept low. With 44" tires and 3.55 gears, the range box will spend most of its life in low, and the bearings will not survive. Then apply low range in the 205, and the 203 spins at a faster rate making the above problem worse.
This has trouble written all over it.
As far as the split in gears, its up to whatever you can buzz the engine at. For laughs, I left the little tires on my orange truck once, (33" bfg mud terrains) and took it for a spin. Literally for a spin, lol. I run 5.13's and took her on the freeway. man that sucker was fast. First gear was a waste of time, and I could actually take off in 4th, but for a laugh, I could let the clutch out in second, smash the gas, boil the rear tires, and hit third, it would pull pretty hard once the tires sort of hooked up, and 4th gear just kept going and going. Lots of fun.
There is something to be said about mechanical advantage............its why many axle gear ratios are available.