LT225/75R16E Tire Inflation Info for 24' and 26' Born Frees

[whemme]

All 24' and 26' models of Born Free Motorhomes generally came equipped with LT225/75R16 load range E rated tires. 

A simple to use tire inflation graph is available at the following website address: http://home.earthlink.net/~whemme/bornf ... lationdata

Also available at this website are 3 links to additional information on RV tires including tire care, RV loading, RV weighing, etc,

[Charlotte]

Bill...Hate to bother you again but need some help on tires. I checked your graph out but I'm still not sure how to handle this. First off I'm having new tires (6) put on next week. (Not because my tires are worn but because I'm seeing little cracks, etc. and I think they are probably about 4-6 years old. Bought my '99 RSB gently used a little over a year & a half ago. I'm going to be traveling through some mountain roads at Christmas time & may run into black ice, etc., so I wanted to ensure to some extent that new tires would make for a safer trip. Anyway, I'm buying the Michelin's at Costco & having them install them. However, how do I know how much to inflate the tires? (I don't know if the installers at Costco will inflate them properly...) I checked at Camping World while having the regular maint. work done & they said they didn't know where I could get my BF weighed. I pass a CHP Weighing Station on the way to CW & thought I could stop there, but I'm told that's not an option. In other words I know I should weigh her in order to know if I'm legal etc., and also to know how much to inflate the tires...but haven't done so. As I travel alone, do not tow and certainly don't carry much in the way of stuff other than the average things (I do carry a spare in the drivers side storage area)....how can I know how much air to put in these tires??? Any help will be greatly appreciated cause I'm at a loss.....

[whemme]

Charlotte,

What you need to do to determine the correct tire pressure to use in the tires in each of the four corners of your Born Free motorcoach is to find a suitable set of commercial weight scales to weigh your unit. Make sure your vehicle is loaded up in down the road traveling condition with full fuel, full fresh water tank, full LP tank and yourself and all the things you normally carry aboard.

I used the services of a local farmer's grain coop which had a 100,000 lb truck platform scale on which I could measure the following weights:

1) Total weight
2) Front axle weight
3) Rear axle weight
4) Weight on left front tire
5) Weight on right front tire
6) Weight on right rear set of duals
7) Weight on left rear set of duals

Open up this Bridgestone/Firestone link to to a 6-page .pdf file document that shows how in detail to do the weighing. You will note that it shows a picure of a CAT Certified Scale. A lot of truck stops such as Flying-J will have this scale or one similar. Tell the scale operator that you want an accurate weighing of your Born Free getting all of the 7 measurement listed above. This will take some time to do properly and you will need to pay the scale operator fairly for his work. If he says he can't or won't weigh the four corners individually - go somewhere else that will.

http://www.trucktires.com/us_eng/librar ... ghForm.pdf

Then you can use my weight graph to figure out how much to inflate the tires in all four corners of your unit.

The results of weighing my 2002 Born Free 26' RSB unit were as follows:

1) Total weight - 13, 260 lbs
2) Front Axle weight - 4040 lbs
3) Rear Axle weight - 9220 lbs
4) Left front tire weight - 2070 lbs
5) Right front tire weight - 1970 lbs
6) Right rear duals weight - 4530 lbs
7) Left rear duals weight - 4690 lbs

Then using my weight graph, the required cold inflation pressure was determined to be as follows:

1) Left front tire - 56 psi
2) Right front tire - 53 psi
3) Left rear duals - 74 psi
4) Right rear duals - 72 psi

So to make it simple, I run 55 psi in the fronts and 75 psi the rears. You can look at my graph and using my weights to see if you come up with the same tire pressures that I did for practice.

[Mike Jean Bandfield]

I'm buying the Michelin's at Costco & having them install them. However, how do I know how much to inflate the tires? (I don't know if the installers at Costco will inflate them properly...)

The last time I bought tires at Costco, they took a very simplistic position - inflate to the max allowed by the chassis mfr. While this guarantees you'll have adequate pressure, it is obviously not ideal. In my case they insisted on this procedure and would not fill them to the pressure I requested. (80 PSI in a bobtail pickup is ridiculous. I was bouncing down the road like a basket ball.)

I checked at Camping World while having the regular maint. work done & they said they didn't know where I could get my BF weighed.

In addition to those places already quoted they have scales at most moving companies, sand/gravel lots and city dumps. Call ahead for availability to the public and for pricing.

I pass a CHP Weighing Station on the way to CW & thought I could stop there, but I'm told that's not an option.

Here in Oregon, you can use the CHP weigh stations if they aren't open. (They leave them turned on. It's a nice courtesy and promotes safety.)

Also, the charts like Bill's are typically the minimum safe inflation pressure. I always add 5 PSI to mine.

Costco has also started using nitrogen to fill tires. It's a nice touch but don't go out of your way trying to maintain them always with nitrogen. It can get expensive and you can't always find it when you want to adjust pressures. With an RV you are more likely to be making frequent pressure adjustments and finding nitrogen can be a pain in the wahzoo. Just go ahead and use regular air. Mixing air and nitrogen is not a problem.

Mike

[Charlotte]

Thanks Bill, Mike & Jean....All the infor. is very much appreciated. Bill, I'm in the middle of a busy, busy city....there are no farmers around me so I'm going to have to do a little more homework on where I can take my BF to be weighed. I don't mind paying a reasonable amount & I know that I should have her packed, filled, etc. when doing this, but thank you for reminding me. I think what I'll do is follow your 55 & 75 psi infor. as I'm sure like Mike & Jean pointed out, Costco will probably put in 80 #'s all around & I'll be bouncing all over. I wish I had more time to do this, but this trip caught me by surprise & I'm trying to fit all the 'have to' things in before I leave...Thanks again ... don't know what I'd do without this website....

[whemme]

The data that I used to generate my tire pressure graph came from a Michelin website and this data will be exactly the same for all manufacturer's making LT225/75R16 load range E rated tires. Mike & Jean Bandfield stated that they add an extra 5 psi to their tires. This does not hurt anything as long as adding that 5 psi does not exceed the maximum 80 psi cold inflation pressure that these tires are rated for. The downside to adding that extra 5 psi in my opinion is that it will just make your coach ride harder.

I also use a Pressure Pro tire monitoring system on my Born Free and I can tell you from experience, that after the tires are fully warned up from driving at least 20 miles, the tire pressure will incease about 10%. In other words, I am seeing typically a 6 to 8 psi increase in pressure from the initial cold setting. I don't really see any need to add that extra 5 psi as I think the tire manufacturers already have an adequate safety factor built into the recommended cold inflation pressures.

[rhively]

Charlotte,

They have scales at most truck stops like Flying J.

[Charlotte]

rhively...Thanks for the input...but there's no Flying J's in my area nor do I remember seeing any along the route I have to take going to Southern California. I'll be looking in the phone book tomorrow to find something close to me...By the way, I was told that Costco sells Michelin but not the same quality as if you go to Sears or another all tire supplier....Does anyone know if that's true? I checked with Sears and used the same tire #'s and they were $300.00 more than Costco. I've already put my deposit down and am now concerned that I've made a mistake.....

[Mel Wilbur]

Charlotte, I don't think you made a mistake. This subject came up at one of our rallies and I then called Michelin and was told that they change the markings on the tires for places such as Costco but the tires are all the same quality. What brought to our attention was the placement of the X in the LTX designation on the tire. The ones in question had the X but it was not directly following the LT. It appears that where you actually buy the tire should not make any difference. You could call Michelin to verify this information.

[Trisha]

For Flying J, just go to their website, they have a map with all their locations right on it.


http://www.flyingj.com/

I have not weighed the corners, only front and back...did that at a flying J CAT scale. My rear end weighs very nearly the load limit for the tires when I'm ready to roll...so I only carry about a half tank of water sometimes. Depends on where I'm going and the conditions. I have more CCC in the front over the front axle so that's where I try to pack the most. And it means that my tire pressure will be pretty close to the limit. I run 75 rear and 65 front. Maybe a little higher in the front if I'm packed to capacity (running right at GVWR).

Feed stores also have scales. I'm waiting to find one of those really cool corner scale things at an FMCA rally. Or maybe I'll find one at Quartzite that we can use? Who knows. Hope so soon. I'd be curious about side-to-side weight.

[Charlotte]

Mel...Thanks for the information about Michelin & Costco. My son made me very nervous when he told me what he'd been told by a Tire Store he buys his tires at. I was trying to be soooo careful to follow the advice given on this website when replacing the tires and mentioned to him that I checked Sears & Costco...etc., etc. Anyhow, I'm relieved that I didn't make a mistake so thanks.....And, I'm going to Quartzite in January for the BF get together put on by Jeff & Linda so maybe I can check my weight again there .... Thanks everyone for all the input...

[Charlotte]

Okay...the deed is done...6 new tires installed by Costco. I'll share the important details for the sake of others who may or may not benefit.
1) Yes, Costco is using Nitrogen. Yes, you can use regular air if you need to adjust your tire pressure. Nitrogen (per Costco) keeps your tires cooler especially over long trips.

2) Yes, Costco does have a deal with Michelin on certain tires, where they make them just for Costco. They are (per Costco) same quality, etc. (not seconds or anything). However, some tires are the same as at any Tire store as Costco has.

3) The tires I originally ordered were NOT what I wanted (nor what I already had on the BF). Thanks to my Son and a LOT of conversations at Costco, finally speaking to a Manager whereby I went out to my BF and read him the entire lettering on my tire and told him that's the tires I want... are those the tires you ordered. (Bad sentence, but you get my intent).
Anyhow, what they'd ordered was NOT what I thought they ordered. The key difference was the word RIB. So Costco had to re-order and did so without any added charge other than the increase in price for the tire, and got them to me today and they are now installed. I have Michelin XPS RIB (commercial tires) size LT225/75R16 LRE. The road guarantee from Costco is very good (no extra cost) and they re-balance, etc. also at no charge. It ended up costing me $1,252.00 for all 6 with everything.

Now...I only have one question for someone to remind me cause I know I've read something about this before...but can't remember.

How do you rotate tires on my RV?

Thanks for all the help. Hope this post isn't too long.....

[Nathan Cook]

Glad that it all finally worked out for you. But back to the original question, Charlotte... what were the final inflation pressures for your new tires?
Nathan

[Mel Wilbur]

Charlotte, Ford recommends rotationg the front tires only. Due to how the rear duals wear they feel it is best to leave them where they are. My personal opinion is that if the front tires are wearing evenly, there is no reason to rotate them, thats just my opinion, i'm sure there are others.

[Dave&JanPotter]

....1) Yes, Costco is using Nitrogen. Yes, you can use regular air if you need to adjust your tire pressure. Nitrogen (per Costco) keeps your tires cooler especially over long trips....

I'm sorry Charlotte but I have to add my 2 cents worth on using nitrogen to fill your tires. For passenger cars and light trucks, it is overkill and not necessary in the least. Costco is using it to attract business, but you will never see the difference. It is used in aircraft and racing applications where the expansion and contraction of the inflating gas must be accurately predicted/controlled under different temperature conditions. Air on the other hand has some moisture present in it and it is this varying amount of moisture that makes calculating its properties difficult as the amount of moisture is not constant from one area to the other. As for compatibility, air is about three quarters nitrogen so there is no incompatibility issue. If Costco is putting it in for free, its fine to use but you should have no qualms about topping up the tire with good old air anywhere in the country nor is there a need for anyone to pay to fill their RV tires with nitrogen. They will never see the difference that it makes. The below article describes it in more detail.

http://www.thestar.com/NASApp/cs/Conten ... 6296450133