wcbcruzer

Actually, swapping in 1500 rear leaf springs came to my mind. I'm glad I'm not the only one who's experienced this. I figure it was just the nature of a heavy duty truck. I'm using load range E tires (factory recommended). I had load range D tires on their previously and I can't say that it was any better. I would think that with an E tire you can get slightly better mileage due to less rolling resistance.

Russ Roth

Are you guys running 80 PSI in your tires? If so that's way more than required when empty and likely why it rides so rough. If you look in your tire manual that came with the rig you only need something like 40 PSI when running empty. Your tires will wear much better also. The 80 PSI is the maximum pressure that your tire can run for maximum weight rating. Not exactly what you want when empty.

Baja

I base my tire pressure on how it wears, it too much on the shoulder, it is too soft, too much in the middle, too hard. For me, 60 in front, 55 in the rear works. I get very even wear on my tires with those pressures.

Russ Roth

That's the way to do it. I don't seem to need that much in mine but I am running 285's so that might be the difference.

wcbcruzer

Same here, and actually I believe those are the pressures I'm running as well.

PaulDaisy

I have the same thing. My tire pressure is 55 psi and my tires are really soft so th bouncing is not as drastic but it is there. And yes, you can see it if you look closely at other trucks. The shocks probably won;t make a big difference - the suspension isn't even compressing without the load in the back. It is like riding in a wagon without suspension at 70 mph - of course its bouncing.
Put 12 sand bags in the back and it will be much smoother. Works for me. Fuel mileage is the same.

high bid

Hydraulics are for ricers....not CTDs.

wcbcruzer

haha... More for beaners. Ricers try to lighten their vehicle with heavier rims, body kits, and stereo systems.

Paul, your absolutely right. The rear springs don't even compress without a load. Has anyone toyed with the idea of swapping in lighter duty rear leafs? At least maybe just the overloads?

high bid

under normal hwy conditions you shouldn't be bouncing....maybe check the shocks??? just another idea.

SIXSLUG

Because of the weight of the Cummins engine your truck requires an "E" rated tire. Do not run lighter rated tires on these trucks, you could experience a blowout or worse. Search the threads on this one!

Kurt

JHew84

A good way to check for shocks being worn out is to peg the brake right before coming to a complete stop. It will transfer a lot of weight onto the front suspension and cause it to dip, if it settles right back out after rising again you're good to go but if it sits there and bounces for a bit it might be time to look into new shocks.

As mentioned previously depending on the spacing of the concrete blocks on the highway the wheelbase of some trucks will catch it just right and cause a rocking sensation between the front and rear. The only way to truly solve this would be to modify the wheel base, but until you do that you can make it less noticeable by doing some of the things mentioned in this thread already. I'd say your best bet would be getting some softer springs for the rear.

SIXSLUG... care to elaborate on that statement? I just find it a little hard to believe that the 5.9L ISB is so heavy it exceeds the weight limit of a D rated tire.

SIXSLUG

The suggested ply rating for the 2500 w/ Cummins engine is 10 ply 'E' rated tire because of the max gvw for these trucks. I read a lot of threads on tires when I first purchased my truck and some of the more informed posters had tire industry experience and explained quite well the reasoning for going with the rec'd tire rating. The 4x4's are heavier in the front becasue of the axle and it was strongly recomended to go with the 'E' rated tires. I'm sure a lot of it has to do with sidewall strength and construction too. Some tire centers like Sears and Les Schwab won't mount tires lesser rated than E on these trucks.

Kurt

dozer12216

JHew84 --- The only way to truly solve this would be to modify the wheel base.. Even simplier would be change speed enough to get out of natural frequency range. JMHO
Trucks will bounce given enough engery input.
removing trailer spring(overloads)(second set above) will not help.
Want ride like a 1500, buy a 1500. Paid for a 2500 or 3500, get your money's worth, and haul a load.