Chinook RV

Looking for suggestions for determining the best tire pressure to run on our 4WD Concourse.

Based on the actual axle weights and the inflation pressure calculator provided by the specific tire manufacturer, we should be using 40 on the front and 35 on the rear. Sound correct?

Also, other than increasing the vehicle weight, does the 4WD have any bearing on determining the correct pressure?

not sure about tire pressure, but would love to see pics of your 4x4? What company did the conversion?

Sounds like you have seen that chart but are still not sure. Here are the questions I would ask you:

1) What is your tire size? (Will be on sidewall.)

2) What is the weight of your front axle when you are loaded for travel (including driver and passenger)?

3) What is the weight of the rear axle when you are loaded for travel?

If you have the stock tire size of LT225/75 R16, Load range E, then you can go by the chart I have posted previously (search tire inflation chart here if you don't have it). If you have a different tire size, or a chart that is even more specific, you can go by that.

I run the stock tire size, and my front axle is around 3200# and rear axle about 6800#. Therefore, my recommended pressure for these tires is about 44# front and 48# rear. So that is the minimum I run - but I do often run around 48# front and 52# rear since my recommended pressures are right near the bottom of the chart. But at least I know what is recommended and am not just guessing.

4WD in and of itself shouldn't make any difference, since this is a function of tire weight rating and the weight you have on the tire.

If you are on a washboard or other "off road" and want to air down (reduce pressure) for a smoother ride, then you can look into that separately (that would stlll hold the same for 2WD though, as far as pressures). On highway or just normal dirt road cruising - it's the chart.

Salem Kroger did the conversion. As far as I know, though, they are no longer in business.

Thanks a lot for the feedback, Blue. Right now I don't remember the exact axle weights and the scale print-out is in the rig, down in the barn. But I did use the actual weights when I consulted the tire manufacturer's chart. FYI - The tires are LT235/85 R16, Load range E.

40/35 just sounds so low to me. I guess I was also hoping somebody else out there with 4WD could tell me what they run.

I have a 2005 with a Quadvan conversion. I have the same size tires as you. I run BF Goodrich KO2's. I gone about 2,000 mile now with these tires we're heading towards Alaska so we have already been on every type of road. When I left Austin I had the pressures set at 65psi.I am now down to 58psi it seems the most comfortable.
In my opinion you need to drive it and see whats best for you and the weight does matter. When I weighed mine it was exactly 11,000lbs 1/2 tank of gas and me in it. Now being fully loaded I'm probably 11,400.

VTSweetpea wrote: June 10th, 2018, 11:11 am Salem Kroger did the conversion. As far as I know, though, they are no longer in business.

At least one of the guys from Salem Kroger is at Whitefeather 4x4 in CA doing 2WD to 4WD conversions, he might be owner. Current cost to covert 2WD Chinook Concourse to 4WD is $25k'ish, but they currently use more modern setup so functionality may be tad better. I looked at one original invoice from I think 2000 and factory 4WD was $10k option.

Are you satisfied with how your Chinook performs off-road in 4x4? How intense off-road stuff have you exposed it to?

Chuck

Sorry, was a duplicate. See next post.

sliider55 wrote: June 10th, 2018, 11:28 amNow being fully loaded I'm probably 11,400.

It sounds like the 4WD conversion adds around 1,000# (?) Or do you have an E-450? I think some of the "native" 4WD were on the E-450 chassis, whereas the typical 21' Chinook is on the E-350. If it's an E-350, were they able to up the GVWR somehow? (Or maybe you just run overweight. If so you're not the first one, for sure.)

On the tires: I think once you know the recommended psi, there is nothing wrong with adjusting a bit (as long as it's in the up direction). I still don't think 4WD will make any difference for a baseline air setting, as long as you go by weight and tire size (as 2WD would do). What matters to the tire is how much weight is on it for a given size/rating. Look at it this way: Our tires don't have different ratings for "drive" or "steer" psi (the duallies are differently rated due to heat buildup because of the proximity, not because they are drive tires).

If offroad and looking to air down, then a 2WD would air down the same as a 4WD - it's just about the "jarringness" of the ride, and about the tire patch on the ground, AFAIK. But I'm assuming you are looking for your baseline highway psi anyway.

Yes. Mine is a E450.

Oh very nice then! 3,000# to go