needlern32724

I have the 4.10 rear. I have just read many posts on the subject of tires, wheels, mpg, etc.

Dollar cost aside, is there a compelling reason for me to give up my current (8k miles) set of stock tires for larger/taller wheels and or tires?

I'll be towing my 5ver(heavy) six to seven times a year and that is my primary concern. Not day to day driving.

What would I need to do if I did go larger/taller? What's a levelling kit?

bulabula

No, there isn't any compelling reason to change out perfectly good tires. Some folks that have 4.10's want to lower their rev's on the highway for presumably better fuel mileage, go to a taller tire that serves the same purpose. If you think the stock tires look silly; then you may have a compelling reason.

A leveling kit is basically a 2" spacer that lifts the front end. Lots of folks have the 315's on their trucks with standard wheels and no leveling kits; some report minor rubbing at full lock, some report no rubbing.

If you go to significantly larger tires, the dealer can to into the ECM and program in the revs/mile of the new tire so your odo and speedo are accurate again.

needlern32724

Thank you bulabula. I appreciate your input.
My tranny runs between 180 and 200 degrees at 75 mph and no rv behind it. Would a larger tire help reduce the temps?

majora

I was seeing the same tranny temps as you so I went to the dealer and borrowed the 04.5 service manual and did some reading. The short story is that the computer does not do anything about tranny temps until the temp is up to 260F. At that point it shifts out of overdrive and will remain out of overdrive until the temp go below 260. With that in mind, I figure that 250 is about a good max for the X-monitor to be set at.

Cheers
Gordon

bulabula

I don't think changing the tires to something larger to lower the engine rev's will necessarily make the trans run cooler. Because the rev's will be different at a given speed, the ECM may shift it differently according to its logic table - which may not be based on common sense logic. Either way, you have to keep an eye on those temps.

I don't have a slush box and am not real familiar with the DC 47 & 48RE's, but if I did and pulled a trailer, I'd run the best syn ATF in it and install a lockup switch if the TC isn't already able to lock up in direct (to help keep the temps in check).

BTW, when my tires wear out, I'll put on some BFG 315's (for looks) after I make sure my truck will still fit inside the parking garage (it seems close right now). My boat trailer is only about 8500 lbs.

But if you're towing real heavy, those 315's (load range D) might exhibit more/excessive rear sway than the stock E's you've got on it right now. Big ballon type tires may have more capacity, but have less lateral stability. I always thought that lateral stability was one of the major bennies of having a dooley while towing. Everything is a compromise.

They do make 19.5's ....

Dave04600

I have 4.10 in my truck I did some math and if you switch the tires to 315's it changes the effective gear ratio to a 3.72.

needlern32724

Thanks Gordon for the temp info. I have my X-monitor set at 240.

Thanks again Chris. I too like the looks of a larger tire, but will keep the current size until replacement time, as I would much rather have the lateral stability. Then will probably go with a larger wheel and as wide as possible.

After my first big mountain tow, I'll see how the tranny fluid is and then look into a synthetic ATF and/or maybe a larger sump cover.

I think the tow/haul button gives me the lock-ability I need for the TC.

Raspy

needlern32724

If you do decide to go with a set of 315's in the future, you might consider a set of H2 takeoffs. They can be had for a great price, the wheels are 1/2 inch wider than the Dodge aluminums and the offset is different too. They are the perfect size wheel for the 315's on our Dodges with no rubbing. It's a matter of taste whether you like their looks, but it gives the truck a whole different stance and MUCH more traction in the dirt.
Also, if you want to keep the truck as low as possble with the bigger tires you can remove the rear lifting blocks to bring the rear down to almost level.
With 315's you can expect a small drop in mileage.

Wetspirit

needlern32724

Thanks Wetspirit. I have seen member's pictures of the H2s and they certainly are something to consider. Looking at them might take some gettin' used to . They sure look like they'd be stable.