Best gear ratio for towing

USMA Dad wrote:
While were on the subject (yet don't want to take over the OP), let me ask y'all this: I'm in a similar situation. I have an '04 2500 5.9 CTD, 48RE tranny, and 3.73s 2WD. Stock tires are 265-70-R17. I'm towing about 16,000 (loaded) with a pin weight of about 3,800.

I added two springs on each side to compensate for the pin weight and increased my tire size to the Michelin XZE 245-70R19.5 (33") for increased tire rating (best I could find in a 17 was 3750). Since I increased the tire size, I've taken my 3.73s to somewhere around 3.5x. The engine also runs around 208* when towing. I have a Bulldog Juice with Attitude and tow in the tow mode.

All of that for this, would I benefit by moving to the 4.10s? If I do make the change, I think I'm back closer to the 3.7x area. My main concern is I have a long trip to NY coming up in May and will have a some sections of grade to contend with. What say all???

BTW, this is a "gearing" question, not a "weight" question! :B

Look at the ratings for your MY with your "new" effective gear ratio. Probably the closest offered was 3.42. IIRC It had a dismal 8800# rating. With your tires, you probably should be in the 4.30 area for max towing.

john&bet wrote:
I am very happy with my '04.5 cdt with 3.73s towing at a gcw of 19,800# in all kinds of terrain from Baltimore,Md to Moab,Ut.,from Charleston,S.C. to Great Falls,Mt.

Do you have the stock 17" tires? My GCW is 23,540 (truck by itself is 7100)

I am very happy with my '04.5 cdt with 3.73s towing at a gcw of 19,800# in all kinds of terrain from Baltimore,Md to Moab,Ut.,from Charleston,S.C. to Great Falls,Mt.

While were on the subject (yet don't want to take over the OP), let me ask y'all this: I'm in a similar situation. I have an '04 2500 5.9 CTD, 48RE tranny, and 3.73s 2WD. Stock tires are 265-70-R17. I'm towing about 16,000 (loaded) with a pin weight of about 3,800.

I added two springs on each side to compensate for the pin weight and increased my tire size to the Michelin XZE 245-70R19.5 (33") for increased tire rating (best I could find in a 17 was 3750). Since I increased the tire size, I've taken my 3.73s to somewhere around 3.5x. The engine also runs around 208* when towing. I have a Bulldog Juice with Attitude and tow in the tow mode.

All of that for this, would I benefit by moving to the 4.10s? If I do make the change, I think I'm back closer to the 3.7x area. My main concern is I have a long trip to NY coming up in May and will have a some sections of grade to contend with. What say all???

BTW, this is a "gearing" question, not a "weight" question! :B

Dodge has had different ratings for the different ratios.
They also have had a rep for weak trannys, especially in the OPs MY truck.
A lower ratio will be easier on the tranny.

As for whether it is worth it or not.. That all depends on how often/heavy one tows, and the terrain coupled with ones performance expectations... Everyone will have a different opinion on this.

JIMNLIN wrote:

bmanning wrote:
Lots of factors need to be considered when debating a gear ratio swap.

True and especially in the OP '03 Dodge/Cummins which had three engine hp/torque options (235/460 or 250/460 or 305/555 HO) and the 47RE and 48RE along with a NV4500 or the NV5600 manual trannies.
Any gear recommendation for anything other than a '03/'04 Cummins doesn't apply in this case.

Not knowing what engine/tranny combo he has makes it impossible for a good recommendation.
I'm not a fan of taller diameter tires which drop rpms. I tow up to 16k with the '03 305/555 HO 3.73 and the NV5600. I added a Edge for towing when they hit the streets in '04. It bumps the power 50 hp or so and 80-100 ft lbs. Very mild and really woke the Cummins up in the 1800-2100 rpm range.
If the OP has the 47 or 48RE tranny with the tall .69 OD gear then it kills rpm and power in a HPCR engine.

I often wonder about those that get the highest gears available, then install larger tires and finally complain of lack of towing power!

:S:S:S

Chris

My previous ram 07 6.7 with manual tranny with 3.73 was great but my 12 ram with auto and 4.10 is so much more.:C

JIMNLIN wrote:

bmanning wrote:
Lots of factors need to be considered when debating a gear ratio swap.

True and especially in the OP '03 Dodge/Cummins which had three engine hp/torque options (235/460 or 250/460 or 305/555 HO) and the 47RE and 48RE along with a NV4500 or the NV5600 manual trannies.
Any gear recommendation for anything other than a '03/'04 Cummins doesn't apply in this case.

Not knowing what engine/tranny combo he has makes it impossible for a good recommendation.
I'm not a fan of taller diameter tires which drop rpms. I tow up to 16k with the '03 305/555 HO 3.73 and the NV5600. I added a Edge for towing when they hit the streets in '04. It bumps the power 50 hp or so and 80-100 ft lbs. Very mild and really woke the Cummins up in the 1800-2100 rpm range.
If the OP has the 47 or 48RE tranny with the tall .69 OD gear then it kills rpm and power in a HPCR engine.

Depends on the speed that you like to tow at.

bmanning wrote:
Lots of factors need to be considered when debating a gear ratio swap.

True and especially in the OP '03 Dodge/Cummins which had three engine hp/torque options (235/460 or 250/460 or 305/555 HO) and the 47RE and 48RE along with a NV4500 or the NV5600 manual trannies.
Any gear recommendation for anything other than a '03/'04 Cummins doesn't apply in this case.

Not knowing what engine/tranny combo he has makes it impossible for a good recommendation.
I'm not a fan of taller diameter tires which drop rpms. I tow up to 16k with the '03 305/555 HO 3.73 and the NV5600. I added a Edge for towing when they hit the streets in '04. It bumps the power 50 hp or so and 80-100 ft lbs. Very mild and really woke the Cummins up in the 1800-2100 rpm range.
If the OP has the 47 or 48RE tranny with the tall .69 OD gear then it kills rpm and power in a HPCR engine.

garyp4951 wrote:
This forum is great, and I appreciate all the info.
Goducks, I looked at my door panel when I got home, and it came with 265-70r17 tires 31.7", and now has 285-70r17 32.5".
Don't get me wrong, the 170k miles truck does great, but what really bugs me is like I said, the 47re tranny feels like the torque is not getting to the wheels until it locks up at 45mph, and then its on. I envy those of you with a manual that have full torque in every gear.

I also run the same size tire as you on my 05 with a 48 auto. The difference is I lock the TC in 3rd and I don't think you can. I also tow 18,000# with mine. I will tell you that if your truck is stock that you would benefit greatly by going back to the stock tire size. My truck ran 70 @ 2000 rpm with stock tires and now 74 with the 285's.