Time for a tune up???

[Midnight Rider]

SO I just got my New ( to me) Expy and I have a question.
It has been a while since I have had a truck frame under me and I am noticing that this has a little bit of a rough ride at sower speeds. I have 20" wheels and THESE TIRES. Here are the things that I would point out for suggestions.

It has 160,000 miles and has been very regularly serviced.
It has a rough ride at slow speeds, Letting off the gas does not really seem to effect it at all,
Punching it seems to smooth it out.
Idle is pretty smooth. Gas mileage is within specs.

If I can offer any additional info please let me know.
I am kinda thinking it may be due for some new plugs, or I just need to get use to the ride.

 

[Poppa Wheelie]

So does it have a rough ride, or is there excess vibration from the powertrain? 2 different things, rough ride could be tires, shocks, bushings, etc. Trucks do have a rougher ride than cars, and low profile tires don't exactly help absorb road imperfections.
If it's vibration from the engine/tranny could be their mounts, could be anything.

 

[Midnight Rider]

My experience with bad mounts and such are very limited, However every time I see them go bad things never get really smooth.
Since this is really connected to the speed I am leaning more towards tires and the stiffer suspension than what I am use to.
If I am going slow it is rough, not bad but there( if that makes any since). Once I speed up to about 55 it is gone.
Lets say I am starting off at a light. It will be rough to get it moving, The tranny will still shift out very smooth. It does seem to vary per road so tires could be it. The shift into second and third seem to have no effect. It is not a constant thing. Sometimes it does it and others it does not
Tomorrow I may try to just put it in neutral while I am rolling and see if things are rough. That way the RPMs can bottom out and I can see how it effects it.

On the interstate this thing s like driving a floating tank, It is a very smooth power. It is just the lower speeds ( or maybe less serviced city streets) that seem to f=give it issues.

I am just not use to buying higher mileage used cars. I may be making a mountain outta a mole hill.

 

[Poppa Wheelie]

Tire pressure? Tires with less sidewall height need more pressure to keep rims off the road, but this also can lead to a rougher ride. Maybe have a buddy drive it and see what he thinks

 

[Midnight Rider]

Good thinking on the tires. It seems to have had a little effect on it when I let out 8 PSI per each. However I put it back in because I do not mind a little rougher ride, I would hate to hurt a rim.

I was talking to someone today that told me " Kirk, you have complained about this same thing with a truck before"
I had to think but he ( my uncle) is right.
I once had a F150 and it had similar issues, It turned out that the shop that it went to was very lazy and did not change the back 2 P.I.T.A plugs. I wonder if that may be the case here. Either way, NO biggie. I will update when I know for sure.
If y'all have any other ideas please send them my way

 

[Midnight Rider]

It turns out that one of my tires is slightly out of round and none were balanced. Now I just need to find a Cooper dealer and see of the one can be handled under warranty