Hopping, skipping, sliding on gravel roads - LT305/55R20 - pressure? Size?

[jus]

Hi all,

Just got a 2019 Ram 1500 Longhorn, air ride, front level (daystar spacers + links), 20” factory rims, with Cooper Discoverer A/T3 tires in LT305/55R20.

I’m used to SUVs, which ride this road fine. But I’m finding the truck is skipping, hopping and sliding at the back on the corrugations, ruts and potholes on this gravel road (say at 50mph).

I aired down to 30psi rear and 33psi front and that made quite an improvement, but I’m still finding the rear to be a bit loose and it’s frankly unsettling compared to SUV driving around here. I’m having to reduce my speed quite a bit comparatively to get comfortable.

Is the problem maybe tire size? Too wide? Or pressures?

Also switched to 4WD High and that helped a little.

 

[Rebelguy2020]

Were the SUVs front wheel drive? You can’t compare a pick up rear wheel drive system to front wheel drives. A pick up is lighter in the rear compared to SUVs, you would notice a big difference if your truck had a load in the bed. It does make a difference driving in four wheel drive because torque is sent to the front wheels, but you it will be a bit harder on gas.
I don’t have air ride on my Rebel, maybe someone with air ride can comment on a better setting for your situation.

 

[jus]

Were the SUVs front wheel drive? You can’t compare a pick up rear wheel drive system to front wheel drives. A pick up is lighter in the rear compared to SUVs, you would notice a big difference if your truck had a load in the bed. It does make a difference driving in four wheel drive because torque is sent to the front wheels, but you it will be a bit harder on gas.
I don’t have air ride on my Rebel, maybe someone with air ride can comment on a better setting for your situation.

SUV I am comparing to is a 4WD Range Rover.

Sure I know the back end is light, but I’m sure there must be a way to get it right that it rides well and feels more secure off-road...

 

[Awood05]

My 2021 Limited with Air ride suspension handles my gravel roads like a freaking dream. (My roads are complete and total trash too) Do you know what load range tire you have? I do know that when I had my Raptor, It had load range E tires on it and I had to run them at lower pressures or I would feel everything. Even just 2 pounds of increase in the tire pressures would change the ride dramatically.

One thing to keep in mind too is trucks typically have less weight on the rear axle which can lead to some funny reactions from the back end. SUV’s are typically closer to the ideal 50/50 weight ratio which does help in the handling aspect. I will say though that the Explorer ST I had was far more rough riding on my gravel roads than my RAM.

P.S. When I drive on my gravel roads I switch the drive into Auto 4WD. Mostly for handling in the corners. (A little lesson I learned from the Raptor)

I hope this helps.....

 

[jus]

Thanks for the insights. Yep they are E rated tyres. What pressures are you running? Do you run the rears lower than the fronts?

 

[Awood05]

Thanks for the insights. Yep they are E rated tyres. What pressures are you running? Do you run the rears lower than the fronts?

On my Raptor I ran the E-range tires at 34 PSI cold. This was 4 PSI lower than the door sticker, but that sticker was based off the factory supplied C-range tires. I ran equal pressures all around, but I know a lot of Raptor guys ran 1-2 PSI less in the rears. I picked 34 because it seemed to give me a decent ride, but didn’t bulge too much. I was worried about uneven tread wear if I went lower with my pressures.

I will say that even the Raptor didn’t ride as smooth as my RAM does on my gravel roads. The RAM has the factory Goodyear Eagle Touring M+S tires on it. (Size 285/45R22) I can’t really find the AT equivalent load range, but I highly doubt they are anywhere near E-range stiffness.

 

[jus]

Thanks! Yeah maybe I need to look into AT tyres with less stiffness / load rating...

 

[ColoradoCub]

Pickups ride like crap on washboard gravel roads, really no way around it. There’s no weight in the *** end of pick up trucks. I spend a lot of time on gravel roads that have holes and washboard in them and you really just have to deal with it. Sounds like your air pressure is fine And it s not the LT tire that is the problem. Also the shorter the pick up the worse it is, meaning if you have the baby bed (5.5 ft) it’s worse than a 6’4 bed or 8’ bed

 

[Biga]

I would trying some weight to the bed 250-300 lbs., should help a lot. Maybe some sandbags.

 

[jus]

Pickups ride like crap on washboard gravel roads, really no way around it. There’s no weight in the *** end of pick up trucks. I spend a lot of time on gravel roads that have holes and washboard in them and you really just have to deal with it. Sounds like your air pressure is fine And it s not the LT tire that is the problem. Also the shorter the pick up the worse it is, meaning if you have the baby bed (5.5 ft) it’s worse than a 6’4 bed or 8’ bed

Thanks, yes it’s the short bed. So do you guys agree with running slightly lower pressures in the rear? I was thinking of actually getting some tougher, 3-ply sidewall tyres due to all the sharp shale around here, would that worsen the problem? Was thinking of a hybrid type design like the Cooper S/T Maxx.

 

[ColoradoCub]

Thanks, yes it’s the short bed. So do you guys agree with running slightly lower pressures in the rear? I was thinking of actually getting some tougher, 3-ply sidewall tyres due to all the sharp shale around here, would that worsen the problem? Was thinking of a hybrid type design like the Cooper S/T Maxx.

Man I’ve never found a fix for this issue other than slowing down, riding the shoulder with one tire, etc. sometimes having 300-400 lbs in the bed makes it better. A pic for reference

 

[ColoradoCub]

Thanks, yes it’s the short bed. So do you guys agree with running slightly lower pressures in the rear? I was thinking of actually getting some tougher, 3-ply sidewall tyres due to all the sharp shale around here, would that worsen the problem? Was thinking of a hybrid type design like the Cooper S/T Maxx.

I also wonder if the spring rate of the air shocks doesn’t add some stiffness or a jarring effect unlike coil springs would.

 

[jus]

E

Man I’ve never found a fix for this issue other than slowing down, riding the shoulder with one tire, etc. sometimes having 300-400 lbs in the bed makes it better. A pic for reference

Thanks, yeah very similar roads!

 

[Sascwatch]

I’ve done several thousand kilometres on gravel logging roads in northern Ontario with my rebel and have found that adding 3-400lbs to the bed makes a huge difference in how the truck handles wash boarded roads. I don’t not have the air suspension, but I have LT tires that I run at 42psi rear and 52psi in the front. I found the tires wear out in the middle at the recommended 55/45psi in the rebel.

 

[soSincerious]

lol wow I thought I had it bad ...

I'm about a 1/4 mile down a gravel road that gets regraded every month or 2 ...

 

[jus]

I’ve done several thousand kilometres on gravel logging roads in northern Ontario with my rebel and have found that adding 3-400lbs to the bed makes a huge difference in how the truck handles wash boarded roads. I don’t not have the air suspension, but I have LT tires that I run at 42psi rear and 52psi in the front. I found the tires wear out in the middle at the recommended 55/45psi in the rebel.

Thanks for the tip - what are you using for weight out of interest?

 

[2019REBEL]

Everybody says throw some sandbags in there well guess what they freeze and slide around. What I do(father taught me this) is go get some tire tubes from a semi or tractor. Cut it in half, put some holes in both ends so you can sew it up(I used a zip tie on one end and string on other end) so you can open it up if you need some sand. Our city supplies free sand with a bit of salt in it. Depending on how much weight you want I would think 2 tubes(cut in half, this would give you 4). Placed on either side of wheel well should give you enough weight.

 

[Sascwatch]

Thanks for the tip - what are you using for weight out of interest?

Most of my logging road miles are put on during hunting season, I’ll have several bags of bear bait and dog food in the back of my truck when I leave the house, and the return trip I have nothing in the back. The extra weight on the way out helps keep the rear end from bouncing around on the really rough sections.

In my old 2wd truck I used to carry 5x5 gallon plastic jugs full of sand blasting media, it has very little moisture in it so if you need some extra grip you can just dump some out under your tires. Make sure you secure it in the bed so it doesn’t become a missile in the even of an accident, over the axle is ideal but takes up a ton of room. I kept it at the front of the bed. Total weight was probably around 300 lbs

 

[RamFan321]

Thanks! Yeah maybe I need to look into AT tyres with less stiffness / load rating...

10 ply E rated tires are very stiff. I'd definitely recommend A/T unless you're towing heavy loads a lot

 

[Scram1500]

SUV I am comparing to is a 4WD Range Rover.

Sure I know the back end is light, but I’m sure there must be a way to get it right that it rides well and feels more secure off-road...

The ride in a Range Rover is hard to beat, you won't find anything like that in a pick up truck