What is the ideal tire size for a 4:10?

[Steve g.]

Hey guys, We have a '92 Ford 250 Diesel IDI 4x4 with 4:10 gear ratio (atleast that's what I think since our axle code is C5).
Right now we have stock tires on it and they'll need replacing soon.
If I understand it correctly the bigger the tires, the better fuel economy you get (and faster you go)... but that's only to a certain limit - say... 1 or 2 inches bigger. Bigger than that and it will be worse.
So my question is, what is the ideal size for tires with a 4:10 gear ratio?
And my second question is, am I totally confused about the whole thing?

BTW, we pull an 8-9k trailer and we work off road quite a bit. I also would appreciate it if someone could post a link to some good tires you would recommend us to get.

Thanks in advance,

Steve

[junior3382]

Actually, the way I understand it... the larger the tires, the worse the gas mileage.... unless the gear ratio is changed to compensate, and if factory is 4.10 then tires match now... smaller would increase mileage slightly, but lose performance just as quick. Again, that is how I understand it, I could be wrong too.... anyways, to maintain OEM drive, i would stay close to factory which should be close to 31's? on that truck? anyways, I would think 32's or even 33's would look nice with a leveling kit... but it is a personal choice. Here is a link for good tires alltogether with tons of user reviews that may help you decide.... A/T in most brand will give decent on/off road abilities... IMO.

[mudseeker]

your both right in a way. if you're heavy on the gas pedal, then yes, your mileage will suffer with bigger tires. if you're like me though and keep the RPM's below 2500 when you take off from a stop, then larger tires can improve your mileage.

i'm not saying 40 inch tires are going to make your truck get 30MPG, but if you stayed within a few sizes from stock then yes.
with the bigger tire, you are doing less revolutions in the same distance compared to a smaller tire.

[stumpuller454]

your both right, more tire on the road the more resistance, yet skinny tires have less resistance that wide tires, you could get some 235/85s or 215/85s that are 10 ply, your truck may not look cool with skinny feet but, taller tires turns the engine at a slower speed in theory increasing fuel mileage, at least at highway speeds...plus its kinda corny but skinny tires cut through the air better... even though lets face it we drive bricks on wheels anyways

[stumpuller454]

jinx! lol we think alike! haha

[Steve g.]

So could I put 33's on w/o a problem?

[junior3382]

I would think they would fit, 33's need at least 8" rims to be safe... most stock rims are 7" tires and 32's would be safer.... now with 8" rims and 33" tires, you might have to trim a tiny bit around the feont fender for steering abilities.... but I can see them working.... trial and error, you know your truck better then I do.... In one of the forums there is a sticky for tire fitment.... I forget where, take a look you might find a more definite answer to that question....

[Lonesome7.3]

This is what I am turning with stock 4:10 gears. I have a Stroke, but I do not think it makes that much dofference. They measure 36 1/2 inches tall. But the weight is the big issue. Even with all of that the truck still wants to stand up off the line. So, 33 will not be a big difference I think.

[mudseeker]

look over these three links in this thread and see if it helps you any.

http://www.truckforum.org/forums/gen...ent-chart.html