In addition to Baxter's excellent comments, you are far, far more likely to lose control of your vehicle traveling through rough spots at higher speeds. Your tires will spend less time in contact with the road if they are bouncing up and down rapidly.

I know this from personal experience. Slow down!!!!!!!!

I was going to suggest a set of those TIRESMIL chains that lynlynch found!

Chain her up, then drop the hammer and let 'er buck!

I'd say it depends on the structure of the roughness, on your vehicle's suspension and on the surrounding road conditions (lane size, other structures around, how many cars are near...).

When I lived in Florida many of the old rural roads were dirt roads with a 'washboard' texture. It was waaay easier on me and the truck I was driving to go fast rather than slow -- but the roads were empty of other cars and there were only scrub palms on the road sides.

I've noticed the same thing crossing railroad tracks. Faster is much better than slower.

It may be smoother, but I doubt you had better directional control at higher speeds.

I understand that wasn't the original question.

Yes, exactly. Thus the caveat about the surrounding road conditions.

If I'm the only one on the Crosstown Arterial at 5 AM, I'm liking speed. At 7:30 with cars all around me, pokey is annoying but safe.

You tell me, Matey. You tell me. <Splutter>

... and that was on a smooth road.

So the lesson here is: don't drive near Stinky Pete.

Dontcha hate it when that happens?

The car was no match for the turtle in the road.

That was not due to a rough road. It was due to Detrick's bad driving.

Hey, nice to hear from you again.

Obviously a defective car... those Italians were probably drunker than Pete when they built it! The driver was probably bombed too...

I appreciate all your learned insight and have decided to go slower rather than faster. While it may seem a smoother ride at a higher speed, I will go slower for the sake of the wear and tear on the car. You guys rock!

If you can foot the fuel bill, you might find a used monster truck, or something from the off-road racing truck series. You should be able to hold the speed limit at moderate comfort levels.

If you can foot the fuel bill, look for a used off-road race truck, or monster truck. That should allow moderate comfort and control at posted speed limits. Good luck.

Might I suggest moving?

Not quite the same as a rough road but I have found that the speed bumps locally are much better taken at high speed ~45mph, going slowly throws the car around more.

I agree with most of what has been said--in general, slow down.

But, brake before you hit the rough parts of the road, speed bump, or whatever and, if possible, coast over them (rather than braking or accelerating).

I think most people know or have learned that through experience, but I just thought I'd mention it for the sake of completeness. Slow down, coast through the rough spot, then re-accelerate--usually you'll find it a lot smoother.

Also, occasionally there may be a sweet spot of speed--if you cross something at the wrong speed, you may match the resonant frequency (or a multiple thereof) of your car's suspension, and you will get a lot of bouncing at that point.

It would make sense of driveing slower. But sailing over a single rough spot with the momentum of speed sometimes makes the ride smoother.

But not necessarily more controlled.

What kind of roughness?

Is it regular, like corrugations or random fracturing or potholes?

What kind of "car"? small, medium, "full size", SUV?

What kind of suspension? fully independent, front independent/rear beam, beam/beam

(what is the "unsprung weight")

How well is it damped? well designed, "comfort" damped, new, worn out ...

What are the tyres? How new? What construction? What profile (or aspect ratio)?

&

How attached to your windshield are you?

How annoying to others do you like to be?

Or every car, at every 'maintenance level' will have a 'best speed' for every kind of 'rough'.

random fracturing (freeze/thaw)

'06 subaru forester

4-wheel independent suspension

Tyres- worn need replacing

Windshields are to be seen and not worn

I am annoying - 60 mph in the granny lane

The Forrester should handle most stuff fairly happily.

If it's not - it's time to look at the damping and for loose bits.

Also new tyres are remarkably better at 'smoothing out' bumps, than old ones. In some cases, new rubber is nearly as "remarkable" as new shocks.

At the risk of WW3 around here - windshield breakage (by rocks) is largely a function of your velocity. Rocks tend to be just 'flicked up in the air" and you provide the impact.

Below 30 mph might be a better idea if they are about.

Slower is usually better, but in this case you may lose her by courting too slow.