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03-13-2021, 11:35 AM
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#21
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Senior Member
Join Date: Oct 2017
Location: Quincy, WA
Posts: 1,504
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I run 100 psi crossfires on my DX3.
Do a cold inflate at 70 degrees ambient and go from there.
I also run TPMS on the crossfires for all four of the rear. I have seen tire temps rise to 118 degrees in August crossing Wyoming. Pressures will also increase to around 112 psi and the crossfires are showing red (as they should --- normal)
When tires cool to ambient most of the time you can see the crossfires in the yellow range on a visual and make your walk around prior to moving much simpler
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Ken and Kathy Redburn
2018 DX3 37TS (The Taj)
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03-13-2021, 11:51 AM
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#22
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Senior Member
Join Date: Jul 2020
Location: Phoenix
Posts: 850
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Ken, that temp change definitely has a huge tire pressure effect, more than I anticipated. I also ran individual tp monitors on each wheel. I ran 90psi crossfires on my Isata-5 and had the same experience as you. Started each day in the yellow, and ended up in the red. I liked the crossfire mostly because of ease of airing up, and the tire equalization effect. I read a lot about mismatched tp on duallys and the wear affect. Thanks for your feedback. Hal
__________________
2021 Force 37TS (Detroit DD8)
2021 Jeep Grand Cherokee Trailhawk
2020 Isata-5 36DS (traded in)
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03-13-2021, 12:08 PM
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#23
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Senior Member
Join Date: Oct 2017
Location: Quincy, WA
Posts: 1,504
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I should have included that I inflate to 95 when ambient is 70. I do this in shop.
Yes the pressure changes due to tire heating are incredible to watch on the TPMS. I was surprised to see that much change. But then at 100 degree outside temp a road surface is going to be HOT
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Ken and Kathy Redburn
2018 DX3 37TS (The Taj)
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03-13-2021, 12:39 PM
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#24
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Senior Member
Join Date: Oct 2016
Posts: 596
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I always go to CAT scales at truck stops to get weighed. If you pull on correctly you will get weights for each axel including trailer axels if you are towing. I think it usually cast about 10 to 15 bucks.
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03-13-2021, 12:44 PM
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#25
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Senior Member
Join Date: Jul 2020
Location: Phoenix
Posts: 850
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Most truck stops, Flying J, Loves etc have scales? I've never looked. BTW, a little off subject, do truck washes at the truck stops do RVs? I've never even paid attention to see if they use huge automatic brushes or by hand. I know there is often a pretty long waiting line. I would think maybe RVs have too much stuff on top. Maybe they don't do the tops. Probably could start an entire new thread on what RVs can do, or not, at truck stops. I'm usually embarrassed to even go through their fuel bays. But with the dual tanks on my Force I guess that will be necessary.
__________________
2021 Force 37TS (Detroit DD8)
2021 Jeep Grand Cherokee Trailhawk
2020 Isata-5 36DS (traded in)
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03-13-2021, 01:48 PM
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#26
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Senior Member
Join Date: Sep 2017
Posts: 223
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Quote:
Originally Posted by Invisibleman
Most truck stops, Flying J, Loves etc have scales? I've never looked. BTW, a little off subject, do truck washes at the truck stops do RVs? I've never even paid attention to see if they use huge automatic brushes or by hand. I know there is often a pretty long waiting line. I would think maybe RVs have too much stuff on top. Maybe they don't do the tops. Probably could start an entire new thread on what RVs can do, or not, at truck stops. I'm usually embarrassed to even go through their fuel bays. But with the dual tanks on my Force I guess that will be necessary.
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There are some that have truck washes. Blue beacon is more hand wash and they do rvs. The worst on the roof at blue beacon is the rinse down which is just a heavy rain.
They run pretty quick at about 10 minutes a truck.
If you are unsure, just ask the wash guys at a spot.
One automatic I found and used, the guys shut the roof wash off after doing the overhead nose.
Don't be embarrassed about going through the truck fuel lanes. Most of them I have talked to really like the rig. Just follow the rule to pull up to the line after fueling, THEN go in to pay if you have to.
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03-13-2021, 03:54 PM
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#27
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Senior Member
Join Date: Jul 2020
Location: Phoenix
Posts: 850
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Not sure what part of the country you are. I've never heard of Blue Beacon.
__________________
2021 Force 37TS (Detroit DD8)
2021 Jeep Grand Cherokee Trailhawk
2020 Isata-5 36DS (traded in)
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03-13-2021, 03:59 PM
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#28
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Senior Member
Join Date: Sep 2017
Posts: 223
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They are a nationwide company. More Midwest, east coast, but do have west coast spots.
Located near truck stops.
Bluebeacon.com.
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Aaron
2019 DX3 36FK
All Electric w/Cab Over
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03-13-2021, 04:18 PM
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#29
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Member
Join Date: Jan 2019
Posts: 54
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Invisibleman- You mentioned cross fire tire pressure equalizers. Question please-if one dually tire gets a puncture, do both tires go flat or is there a check valve to avoid this?
Thanks
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03-13-2021, 06:34 PM
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#30
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Senior Member
Join Date: Oct 2016
Posts: 596
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I’m not sure if most truck stops have scales but a lot of them do.
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03-13-2021, 07:16 PM
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#31
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Senior Member
Join Date: Jul 2020
Location: Phoenix
Posts: 850
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There is a check valve to prevent that. Below is their website. They have good info and help videos there that explain how they work.
Crossfire - Dual Dynamics
__________________
2021 Force 37TS (Detroit DD8)
2021 Jeep Grand Cherokee Trailhawk
2020 Isata-5 36DS (traded in)
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03-13-2021, 07:27 PM
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#32
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Wanderluster
Join Date: Feb 2021
Location: FL
Posts: 174
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The best way to determine your proper tire pressure is:
1. Weigh your coach, as it is normally driven, i.e. full fuel, fluids, cargo, passengers, etc. Get your front axle and rear axle weights. CAT scales are easiest for doing this, but anywhere that can measure front and rear separately.
2. Once you have your front and rear axle weights (and assuming it is within the max axle weight capacities rated for your coach), then do this:
a. For front axle, divide by 2. So, if your front weight is 12,000lb, then your single tire weight is 6,000lb.
b. For rear axle, divide by 4 (for duals). If your rear weight is 22,000lb, then your single tire weight (used as duals) is 5,500lb.
3. Then, locate the load/inflation tables for the brand/model/size of the tires you have on your coach. Every major tire manufacturer publishes these tables. Pay close attention to the load rating (F, G, H...) because the same size tires with different load ratings may have different tire pressures. Find the weight column on the chart that is closest to your weight, but still above it, and see what the recommended PSI is for that weight.
For example, I have Toyo M154 tires, 295/75R22.5 load rating H/16 ply. The Toyo load/inflation table says that my front tires should be at 100PSI, and my rear tires should be at 95PSI.
When my tire shop installed the new tires last week, they put 110PSI in all the tires. Kind of a harsh ride. Much better after I aired down to 100 in the fronts and 95 in the rears.
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03-14-2021, 11:13 AM
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#33
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Senior Member
Join Date: Oct 2017
Location: Quincy, WA
Posts: 1,504
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Quote:
Originally Posted by Glampen
Invisibleman- You mentioned cross fire tire pressure equalizers. Question please-if one dually tire gets a puncture, do both tires go flat or is there a check valve to avoid this?
Thanks
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No both tires do not go flat. The crossfire unit isolates the damaged tire. It is advisable (IMO) to run with tire pressure monitoring in addition to the crossfire units
__________________
Ken and Kathy Redburn
2018 DX3 37TS (The Taj)
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03-14-2021, 04:05 PM
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#34
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Senior Member
Join Date: Jul 2020
Location: Phoenix
Posts: 850
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So I wanted to get some clarrification about the whole tire pressure thing. As we all know the tp at ambient off road temp is 10-15 psi less than what you may have when you are warmed up to driving speed and depending what part of the country you are and the time of year. So when we are all saying what tp we are running, does that mean your warmed up highway temp pressure? I am assuming so, but just wanted to clarify that. Because it is something of a technique to get the tires in that sweet spot, and I am assuming pretty much no one is out there everyday making pressure adjustment depending on where they are or what the road temp is that day. Save that for NASCAR pit crews. Listening to the comments on this thread, I am thinking the typical sweet spot decent ride, warmed up average temp may be a good spot to look for is 95psi. Right? And I'm referring to the M2 chassis.
__________________
2021 Force 37TS (Detroit DD8)
2021 Jeep Grand Cherokee Trailhawk
2020 Isata-5 36DS (traded in)
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03-14-2021, 04:22 PM
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#35
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Senior Member
Join Date: Sep 2020
Posts: 575
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Quote:
Originally Posted by Invisibleman
So I wanted to get some clarrification about the whole tire pressure thing. As we all know the tp at ambient off road temp is 10-15 psi less than what you may have when you are warmed up to driving speed and depending what part of the country you are and the time of year. So when we are all saying what tp we are running, does that mean your warmed up highway temp pressure? I am assuming so, but just wanted to clarify that. Because it is something of a technique to get the tires in that sweet spot, and I am assuming pretty much no one is out there everyday making pressure adjustment depending on where they are or what the road temp is that day. Save that for NASCAR pit crews. Listening to the comments on this thread, I am thinking the typical sweet spot decent ride, warmed up average temp may be a good spot to look for is 95psi. Right? And I'm referring to the M2 chassis.
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When discussing tire pressure for normal folks (us) it should be based on cold fill pressure at resting ambient temperature. Load inflation tables are based on this and the tire manufacturer accounts for the rise in temperature from driving.
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03-14-2021, 04:25 PM
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#36
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Wanderluster
Join Date: Feb 2021
Location: FL
Posts: 174
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Quote:
Originally Posted by Invisibleman
So I wanted to get some clarrification about the whole tire pressure thing. As we all know the tp at ambient off road temp is 10-15 psi less than what you may have when you are warmed up to driving speed and depending what part of the country you are and the time of year. So when we are all saying what tp we are running, does that mean your warmed up highway temp pressure? I am assuming so, but just wanted to clarify that. Because it is something of a technique to get the tires in that sweet spot, and I am assuming pretty much no one is out there everyday making pressure adjustment depending on where they are or what the road temp is that day. Save that for NASCAR pit crews. Listening to the comments on this thread, I am thinking the typical sweet spot decent ride, warmed up average temp may be a good spot to look for is 95psi. Right? And I'm referring to the M2 chassis.
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I only measure my tire pressure when the tires are cold - meaning I haven't moved in at least several hours. Usually, when I use my tire pressure gauge, the RV has been sitting at least overnight, and I do it in the morning. Cold also means whatever the ambient outdoor temperature happens to be - whether it's 50 degrees or 90 degrees. That means I do adjust tire pressures from winter to summer. Typically, your tire pressure will increase or decrease about 1 PSI for every 10 degrees of temperature change.
So, if I understand what you're asking - I would suggest you DO NOT measure your tire pressures when the tires are warm - meaning already driven. There are too variables - outside air temperature, road surface temperature, sun exposure, speed, etc.
Best practice - take your tire pressure in the morning, before you've driven anywhere, before the sun hits your tires - and get them at the proper PSI for fronts and rears. Do not worry about what pressure they are at after they are warm - it will be 4-6 PSI more depending on the above factors.
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03-14-2021, 04:37 PM
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#37
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Senior Member
Join Date: Oct 2018
Posts: 1,208
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What he said^
__________________
Joe & Cynthia
2021 Dynaquest XL 3801 TS Cindy 'B'
2021 Jeep Wrangler Unlimited Rubicon Diesel
“Breathe in, Breathe out, Move on”
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03-14-2021, 04:37 PM
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#38
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Senior Member
Join Date: Aug 2017
Location: Marysville, Ohio
Posts: 1,765
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Only 37 post on this one so far. Let’s get with it folks.
__________________
2008 Dynaquest 340xl
Bill and Carol
Retired mechanic
US Army Veteran 🇺🇸
Previous coach 2017 Isata 3RW
Also,3 Diesel pushers, 1Bvan, 2 class Cs
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03-14-2021, 04:49 PM
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#39
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Senior Member
Join Date: Jul 2020
Location: Phoenix
Posts: 850
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I watch my tire pressure live on the TPMS. Its new to me, even after 37 posts Bill, that the manufacturer recommended pressure is based on "cold fill pressure." Here in Az you can go from 70 degrees in the morning, to 100+ degrees and every pound of 10-15 psi increase after you get going. I would have thought the manufacturer, and everyone else, is talking about running pressure after the tire is up to temp. Now I am not so sure.
__________________
2021 Force 37TS (Detroit DD8)
2021 Jeep Grand Cherokee Trailhawk
2020 Isata-5 36DS (traded in)
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03-14-2021, 04:59 PM
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#40
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Senior Member
Join Date: Jul 2020
Location: Phoenix
Posts: 850
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A quick search of tire manufacturers recommendations does, in fact, suggest setting tp at ambient temperature. Even though that makes absolutely no logical sense to me at all. Tires run in Northern climates are going to be consistently in a totally different range. especially at different seasons, than those in the southern climates. It seems this just isn't a black & white subject.
__________________
2021 Force 37TS (Detroit DD8)
2021 Jeep Grand Cherokee Trailhawk
2020 Isata-5 36DS (traded in)
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