2013 3500 DRW Suspension like a brick after new tires

[Igottaroll]

As it says: 2013 DRW crewcab long bed. I had a set of Ironman A/T's 20", LT275/65R20 126/123/Q with bilstien 5100's all around, I ran empty around 60-65lbs air pressure rear & 65-70 in front (empty except the 50 gal aux fuel tank & 350lb 5th wheel hitch) The truck rode awesome, I have about 40k miles on the shocks.
Truck rode great when I was pulling heavy also 24K 5th wheel with tires at 80.
I put on a new set of the same tires (all 6) had it aligned & I adjusted the tires pressure to 60 on rear 70 on front & Wow every bump feels like a brick especially in the rear. (and I mean every bump) The shocks look great no leaks, not loose, I checked coils in front & leaf springs in back (all stock) no cracks & everything appears to be tight, but this is real night & day difference in the ride.
Currently at 160k on the clock.

I have been considering new Thuren Coils & track bar, etc. & will go that route, but this doesn't make any sense to me.

Any suggestions?

 

[AH64ID]

What’s your RAW? If you’re empty you can probably go lower on pressure.

I’m getting a good laugh out of your Amsoil trans fluid temp comment thou…. If you actually saw a 50° drop something was/is wrong.

 

[Ozymandias]

65psi on an empty Truck OMG the ride must be horrible.
35psi is plenty enough for an empty bed.

 

[Cummins12V98]

Stock DRW tires I run 80 front and only 30 rear running BobTail. 6k pin I bump rears to 65-67 and don’t touch fronts. I get excellent ride and even tread wear.

 

[BigPapa]

So, same tires (just newer), same air pressure, and no other changes, but now a noticeably harsher ride?

 

[Topzide]

What alignment specs did you have it set to? You should have a copy of the Thuren specs when you had done. That way you'd be at near zero toe which is the way these trucks work the best at. And the air pressure in the rears when unloaded is way too high! I'm running 50 in the rears with 55 in the front. I've got a 100 gal tank in the bed with crossover tool box.

 

[Igottaroll]

What’s your RAW? If you’re empty you can probably go lower on pressure.

I’m getting a good laugh out of your Amsoil trans fluid temp comment thou…. If you actually saw a 50° drop something was/is wrong.

New to using the forum so hopefully I get this right. No I never had any trouble with my transmission but hand to bible normal operating temp dropped 50 degrees

 

[Igottaroll]

What alignment specs did you have it set to? You should have a copy of the Thuren specs when you had done. That way you'd be at near zero toe which is the way these trucks work the best at. And the air pressure in the rears when unloaded is way too high! I'm running 50 in the rears with 55 in the front. I've got a 100 gal tank in the bed with crossover tool box.

Yes, I did utilize the Thuren specs for the alignment, the confusing part for me was it didn't ride like this previously with similar air pressures, I will drop it down to 50 in rear & see what happens it's the only guestimate I have at this point.

 

[Igottaroll]

So, same tires (just newer), same air pressure, and no other changes, but now a noticeably harsher ride?

Yes. crazy harsh. As I said on another post I am going to drop to 50 in the rear & see if it makes a difference, maybe where it needs to be with new..but not last time.

 

[Igottaroll]

Stock DRW tires I run 80 front and only 30 rear running BobTail. 6k pin I bump rears to 65-67 and don’t touch fronts. I get excellent ride and even tread wear.

Do you rotate yours at all? My other truck I do, but it's not a DRW.

 

[Igottaroll]

65psi on an empty Truck OMG the ride must be horrible.
35psi is plenty enough for an empty bed.

Between the auxiliary tank with fuel & 5th wheel hitch I have a solid 750lbs (50 gal x 8lb +350lbs) I'm going to try the lower pressure, just wanted to make sure I wasn't missing something else.

 

[BigPapa]

Yes. crazy harsh.

I’m wondering if something was damaged, or shifted and didn’t shift back, when the truck was lifted to install the new tires. Is the rear suspension all stock? No air bags, traction bars, etc? Stock shocks?

 

[Igottaroll]

I appreciate those that chimed in thank you, I will give the lower pressures a shot tomorrow & get back to everyone on it.

 

[Igottaroll]

I’m wondering if something was damaged, or shifted and didn’t shift back, when the truck was lifted to install the new tires. Is the rear suspension all stock? No air bags, traction bars, etc? Stock shocks?

Bilstiens 5100 all around, I took a serious look see on the suspension, shocks, etc didn't see any telltale signs of any changes Otherwise yes everything stock

 

[AH64ID]

New to using the forum so hopefully I get this right. No I never had any trouble with my transmission but hand to bible normal operating temp dropped 50 degrees

What were the trans temps before and currently? The fluid has no bearing on operating temp, as your trans uses a thermostatically controlled cooler. Temps should be the same with the OEM fluid and Amsoil. I haven’t yet switched my ‘22 to Amsoil, but I did on my ‘18 and there was zero change in operating temps.


As far as air pressure, 50 is still too high if you’re empty. 35 is the lowest recommended pressure for highway speeds on LT tires. Even at 35 psi your tires are good for a RAW of 7,580lbs. With the size tire you’re running you only need 50 psi to meet the RAWR, so anything over that is either overinflated or overloaded.

If you’re just running around town empty I’d probably run 25 psi, and bump it to 35 for highway driving empty.

 

[Igottaroll]

What were the trans temps before and currently? The fluid has no bearing on operating temp, and your trans uses a thermostatically controlled cooler. Temps should be the same with the OEM fluid and Amsoil. I haven’t yet switched my ‘22 to Amsoil, but I did on my ‘18 and there was zero change in operating temps.


As far as air pressure, 50 is still too high if you’re empty. 35 is the lowest recommended pressure for highway speeds on LT tires. Even at 35 psi your tires are good for a RAW of 7,580lbs. With the size tire you’re running you only need 50 psi to meet the RAWR, so anything over that is either overinflated or overloaded.

I'll have to look that up in the ole maintenence book, I haven't towed in months & generally drive my other truck for around town & work (should have been way south 2 months ago & about now be thinking about getting back here) I will get back to you on this. and zero exageration 50 degree and I pulled a much lighter 5th wheel when I established my benchmark & was pulling 8k heavier when I changed the fluids

 

[AH64ID]

I'll have to look that up in the ole maintenence book, I haven't towed in months & generally drive my other truck for around town & work (should have been way south 2 months ago & about now be thinking about getting back here) I will get back to you on this. and zero exageration 50 degree and I pulled a much lighter 5th wheel when I established my benchmark & was pulling 8k heavier when I changed the fluids

My Aisin’s get hotter then most since I do a fair amount of towing with the TQ converter unlocked and even then they don’t get +50° over the normal temp. These trans run 163-167° all day, every day unless you’re in 1st or 2nd unlocked, such as city traffic or slow hill climbs.

Even with mine running hotter it’s the same with or without Amsoil.

Looking forward to seeing what your logs show.

 

[Cummins12V98]

Do you rotate yours at all? My other truck I do, but it's not a DRW.

no rotation on rears. Fronts leaving wheels in place moving tires side to side same rotation.

 

[bcbender]

I haven’t yet switched my ‘22 to Amsoil, but I did on my ‘18 and there was zero change in operating temps.

These trans run 163-167° all day, every day unless you’re in 1st or 2nd unlocked, such as city traffic or slow hill climbs.

That's been exactly my experience also... no matter how hard I'm towing.. I've never been above 167 unless Im pulling my dump or 5er around town in stop and go where the TQ is unlocked.. No difference switching to Amsoil and next year with the second change and filter it should be mostly all Amsoil...

 

[Ozymandias]

What's the DOT date on the "new" tires? Maybe you got some old hard salamis.

 

[Cummins12V98]

Almost 68k on these.