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Old 09-15-2009, 12:30 AM   #1
5WRon
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19.5 rims on BigSky

Hi again all,

I currenty have 16" rims and two 7,000lb axels. After a scary blowout (and reading a whole lot of blogs) I'm considering going to a 19.5 rim with a Michelin 225/70R19.5.

Please give input if you have done this upgrade with the rims. I have called and emailed DexterAxel and am waiting for a response. I have also called and talked to Michelin and they would warrenty and recommend this combo. Keyston said they felt if would fit but didn't know for sure. I have also measured the height and width plus center axel to center axel and it seems I would have room.

I did consider going to a 17.5 rim but decided against this after searching the web (including here) and I just didn't feel safe with the tire combo and weight ratings I found. Still too many reported blowout for me.

Thanks and safe travels to all,

Ron
 
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Old 09-15-2009, 05:43 AM   #2
skypilot
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Ron: I just looked at the diameter of the tire on the Michelin web site and compared it to the XP Rib 235/85R16 that a lot of have their units. At 32.2 inch diameter, they are the same. Given that, spacing between the wheels should be fine -- I'd be concerned about the clearance between the tires and the shocks and other mounting hardware -- the back spacing on the rims would have to be carefully determined to ensure that the tires don't run on something back there. That said, that then could create another problem if the tire/wheel combination is too far out -- clearance to the fenders as well as added stress on the axles. Given all this I recommend you talk to an axle / spring shop and see what they feel the running gear can handle. A lot of variables to be considered in changing things out that much I feel.
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Old 09-15-2009, 08:49 AM   #3
PSFORD99
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The heaviest Big Sky is 16200 GVWR, with a modest pin weight of 2500 the most you are going to have on your axles is 13700 or 3425 per tire everything being egual. 17.5 tires and wheels will get the job done and then some ,here are the specs.You have bascially two sizes to choose from on tires, and two wheel ratings.

Goodyear LT 215-75R-17.5H weight rating 4805 @ 125 psi.


Goodyear LT 235-75R-17.5H Weight rating 6005 A 125 psi.

Wheels 17.5 x 6.75 weight rating 4850

Wheels 17.5 x 6.75 weight rating 6050


Either setup would do nicely under that Big Sky, one drawback if you go the 6050 wheels is that you will have to change the studs to 5/8, IMO 6050 is getting a little carried away 4850 is well beyond your weight needs or mine.I can see no reason to even consider a 19.5 tire and wheel. I plan on many miles in the future , so 17.5 is my choice over a G 16" tire upgrade or the E rated on 16" that I have now.

I have read many tire failures but 17.5 4805 or 6050 lb rating has never been mentioned in anything that I have read. Could you reference where you read these tire failures on 17.5. From everything I have read 17.5 pretty much puts the tire failure issue to bed on the weight we are towing, and again would be the choice for my fifth wheel.

On edit could it be the G rated tires on 16"rims that you are are refering to as having failures, that I have read about.
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Old 09-15-2009, 01:53 PM   #4
Delaine and Lindy
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I had the Michelin 19.5 on the Chevy 4500 great tires. However I think the issue will be the height. Our 5th wheel is much heavier than the Big Sky and we have Goodyear G114's on 17.5" rims. The Goodyear G614's would be all you need. But if you want extra weight carring I would go will the tandem set up would be much easier than the 19.5's, by the way the rims were 10 lugs. But the G614's would be more practical. I had the G614's on our Cambridge 358 (heavier than the Big Sky) and never had a tire issue and they had over 22,000 miles on them and still looked new. Good Luck on your decision. GBY.....
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Old 09-16-2009, 05:19 AM   #5
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I think that the diamiter of the tire might change the circumferance along with the space between the two tires, I could be wrong, it seems like a long way around to try and solve a problem that will cost you plenty of money. I would invest in tire monitors, and not the ones you screw on the valve stims either, the ones that mount on the inside of the tire to the rim, if you have low pressure or extreem temperature it will warn you in plenty of time to prevent damage to your RV under carage, and god knows what else the tire can damage.
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Old 09-16-2009, 09:10 AM   #6
5WRon
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Hi all,

I didn’t want to go into many other areas, but it seems that we all have questions and go there at times. So, I will try to answer some of your questions. This is a long so I apologize to you at the beginning.
I have spent about 8-10 hrs searching websites on Good Sam, FMCA, Escapee, RV.net, and Montana Owner’s Club (and a couple of others that members have suggested) . I have looked at to many cmts to list (and my eyes are going bonkers with my loss of brain power). I used many search items including tire manufacturers, tire sizes and some action verbs included. I did scan a lot and probably missed much.

Everyone has an opinion and I do respect that. I submit that I do not know anything and start from scratch. I do realize that most posting are about items that go wrong, not all the time, but most by people looking for help. I have come to the trough many times to find answers from you adventurers for things that have gone wrong on my rig or trip. I do realize that there are probably a whole lot more item/tires that people don’t have problems with and don’t post. So, I take what I want and leave the rest for my future problem questions.

Inflation issue:
I was an assistant OTR DOT Allied Vanlines driver years ago. So I took my tire habits from this history. I do have a heavy truck tire gage and use it to check all my tires (truck and rig) before I leave a campground. I always have the tires at their required PSI (80lbs for these) and make a visual inspection every time we stop for fuel (I also use the gage and hit each tire to hear them…you can hear a difference if a tire is low…and yes, one of my degrees are in music). I purchased and used the ‘slime’ tire inflator (230psi rechargeable air compressor). ) I also have (and use) tire monitor systems (Pressure Pro for the 5th wheel and the OEM computer tire monitor on the 2500HD truck). I had tires inspected (with brakes) at 2,064 (5 months) – 4,480 (12 months) – and had the blowout at 6,325 miles (13 months). So I have had them inspected by RV dealers too.

Rig weight:
I do not have a washer and dryer or a generator. I do have a second AC over the bedroom. I dump all three tanks BEFORE I travel on the road (why waste the diesel to pull this weight when you don’t have to??). I had the 5th Wheel weighed at the Gillette, Wyoming Rally last year about a month after buying it. It weight was 13,438 lbs (under the axle and rig weights). I have since replaced the two back heavy recliners and CRT TV in the bedroom. I have added bedding, food and other items since then. No, I have not had this weighed and should (will) do this ASAP. I do feel that I’m still not overweight nor was ever.

Driving speed:
Most of the times I travel at 5 miles less than the speed limit to be a courteous RVer. I must admit that I have on occasion exceeded this rule but very, very rare. I have gotten used to safely traveling at this speed to enjoy the scenery. I also pull over to let other pass.

The problem/ situation:
I had one front right CRT tires separate from the sidewall and create a 6/7 inch ripped bulge. The tire did not lose air and I immediately found a campground to safely stand down. NOTE: It so happens that another 5th wheel was already in this CG and did have two tires blowout which caused extensive damage to their under carriage/wiring/molding/mountings, etc. I did personally see this so my immediate mind and search was zeroed in on top lined safety for my wife, myself and others on the road while searching for replacement tires. Oh, they did put the 5th wheel on a trailer yesterday and took it away for repair.
I contacted my roadside assistance and they helped me in locating an expert tire dealer/business (local people said good things about them) to change the tire with my spare and evaluate the problems. They came out to the rig, removed the tire and was about to put the spare on when they noticed bulges in the rear right tire (the one behind). I also saw this and asked them to make recommendations. They also stated (and I inspected the tire) and found no other damage to the tire and this separation/bulges were caused by a manufacturing problem. They went back and called me later informing me that they would suggest the XPS Michelin (he had replaced many RVs with this tire without one complaint). I did some more research on the net and could not find one Mic tire separation and most 5th Wheels which had these installed loved them. They came back out and installed 4 XPS Mics on my 16” rims. Well, I had previously called and emailed Michelin when I had a return call from Michelin. I gave him all the weights/stats and he stated they would neither recommend nor warranty this tire for these weights. He also stated they receive warranty claims which they deny because this tire is under the required weight for the rigs and axle. He then made a statement that the insurance companies would be asking the same questions also. Well, I also did more research and found that these XPX Mics were 458 lbs under the minimum weight requirements. My thought process was why would I even consider any tire that is under the axel/tire weights and one that the manufacture would not back?
So, again with safety in mind, I’m back on the net and the tire dealer is looking at what he can put on that meets the minimum standard. As I was reading (and receiving emails) about tires the question of rim size came to the forefront. It seemed there were a lot less problems with 5th wheels which went to a 17.5 rims than 16s. So I started searching this, and yes, I did find a lot of people who were happy with this size and had fewer problems (but there were a couple of people who did have problems). I found two posts from 5th wheel people which went to the 19.5 rims. It was suggested that the larger rims would be safer (again I didn’t know anything about this nor looked at rim size but started). I again called Michelin, received a call back, and was given two tires which would meet the weights requirement with 17.5 rims. It was during this conversation that 19.5 rims were suggested as a safer alternative (if the rig/axle/brakes could handle this). I also found on another forum where the 19.5 rims were the best choice with older motor homes and it was because of the addition of slides equaling more weight that they went to a larger rim. I also found two BigSky/Montana owners who went to the 19.5 rims without any problems (I know, some will compare two against thousands but I only tell what I found).

I called Dexter Axles (my axle manufacturer-8 bolts) and was told the 7,000 lb axle would carry the 17.5 and 19.5 rim. He said both was a good upgrade but would choose the larger one would provide a better foundation (again I didn’t know this). The only problems he could see (and another poster’s response) were could the brakes handle the larger rim, and would the larger rim/tire fit safely on the rig, proper clearance between the tires and shocks, and that the back and top of the tire does not rub/run on something back there, and clearance on the fender well?

I called Kodiak (which are my 13” disk brakes) and they said the brakes would handle both axles. They recommend that I have the brakes checked at shorter intervals (like 4-6 months) to ensure that they keep providing safe braking conditions.
The tire dealer who put on the XPS tires called back and suggested to go to 19.5 rims with Michelin XZE tires. Until this time I had not talked about 19.5 rims with him.

I have also personally talked to Goodyear, Carlisle (they have requested to have the two tires sent back to them for inspection and a possible refund…they did say that they would not replace all four), Hankook , Keystone, and a couple of others that I can’t remember.

The current state of affairs:
I’m waiting for the 19.5 tires and rims to arrive Thursday night. The tire dealer will come back out to the rig on Friday or Saturday and replace the current rims and tires. At this point I still don’t know if I’m making the right decision but it is mine and I will live with it. If I see, after carefully looking at the tires and areas which surround them, that they will not work I will not purchase them…bottom line. And start all over again.

I left out much more info and thought processes I went through. I did feel overwhelmed at times at all the choices and personal versions of experiences. I state that I do not profess to be correct or the tire/rim expert because I’m not…just a simple RVer looking for suggestions to solve problems. I also know there are many happy owners of all kinds of manufactured products and do not imply they are wrong, nor that I’m right. I tried not to point to any one person nor downgrade any products. If I did I apologize. I also did not give you stats which you can find on the internet (rig, tires, axles, rims, lugs, brakes, etc.).

I just wanted to try and relate to all of you what I went thru, going thru and how I made this decision. I know I missed a lot of information but that’s the way it happened. I also did not want to address the LR/ST/LT issues and leave that for others to discuss (I just can’t address/cmt on something I have no personal knowledge on or experience with). I had to go on my gut feelings knowing that I will make wrong decisions at times.

Thanks to all of you and I’ll keep you informed/updated on my thoughts and findings.

Happy and safe travels/adventure to all,

Ron
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Old 09-21-2009, 06:02 AM   #7
5WRon
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Follow up as promised:

I had new rims and tires mounted on Saturday, 19 Sep. The installer and I crawled around on the ground and checked clearances from every angle (no problems). The rig’s new height is 1” more (go figure).

Here are the stats:

RIMS”
Vision
Hauler
Style: 81
8 Lug
DOT-t Et
Machined Clear Coat
MAX Load (per rim): 4500 Lbs
(C) BFF 19337
(M) 08/20/07
(H) 0819111
NJYH
Torque at 110 lbs according to Keystone, Michelin and Dexter.

TIRES:
Michelin XZE
225-70R-19.5
Load Range: G (14 ply)
Cat Number: 91043
Diameter: 32.2
Width: 8.9
RPM 646
Tread Depth: 17
Max Speed: 75 mph
Max Load per tire: 3970 lbs at 110 psi
Tire Weight: 60.9 lbs

I know you might think this is over kill. It is my decision is to be as safe as I can and not kill you, my loved ones or myself. I have some pics I would be glad to send to your email address.

Happy and safe trails to you all,

Ron and Linda

NOTE: Carlisle tires pickup two for their inspection. Said they would not replace/refund on tires that had nothing wrong with them.


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Old 09-22-2009, 07:05 AM   #8
5WRon
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A little more info.

I did upgrade to the 19.5 rims and Michelin XZE tires. I’ve already received compliments and inquires from a couple or 5th wheel travelers in the park we are now. Not to mention the ‘peace or mind’

I have and others have commented on. The cost is worth the mind set for me (just have to eat out less often…but our dog will eat like a king…as always).

The second time I talked to DexterAxle, they told me my axle could be 8k (it does say 7k on the brochure and Montana/BigSky packet we received). However, at times they would send out to the manufacturers axels in stock which could be 8k. Regardless, they did reinforce the 7k axle will handle my new rim and tires just fine.

I did use the same lugs and center cups. The ones provided were too short and the lugs we have were top of the line so why buy others (saved a few $$$). The tire dealer is ordering deeper center cups and will send them to us (where ever we are located). We can then decide to keep the ones we have or use the new ones.

Another item which I found was addressed and talked about a lot from numerous sources (including two different tire dealers) was the heat issue. It seems that some tires run hotter than others which may lead to quicker sidewall deterioration, tread wear, and over inflation issues. I plan to keep my tire pressure at the recommended max. This may be a good topic/subject for discussion. I just don’t know how this could be documented with all the different tires/road conditions/weights/etc. and other variables to consider.

Well, again safe travels to you and thanks for all your suggestions and thoughts,
Ron
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