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Old 10-05-2008, 04:41 PM   #1
jeffwilliams1954
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Attention All Tire Professionals!

I need to know if I can put in place of my OEM Mission 235/80 R16 tires with the Goodyear 235/85/R16 G614RST tires. Does the 80 mean that it is a six inch rim? The Goodyear website says the G rated 235/85 needs a 6.5 inch rim. Any help would be great. Thanks
 
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Old 10-05-2008, 04:56 PM   #2
ggranch
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Not a professoinal but the 80 and 85 refer to the profile of the tire sidewall stated as a % of the tread width.The 235 is the tread width in mm. The sidewall of the tire is 80% of that number. The Goodyear tire is 5% taller than the Mission making for a slightly larger diameter. This whould not be a problem unless your axels are extremely close set. Bob
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Old 10-05-2008, 05:11 PM   #3
jeffwilliams1954
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That makes sense. Thank you for clarifing this for me. The Goodyears should work just fine.
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Old 10-05-2008, 05:13 PM   #4
skypilot
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Bigger question (and problem) is that the Goodyear tires require 100 to 110 psi (max per the sidewall is 110 psi). You need to ensure that your rims can handle that much pressure (many of the steel wheels as well as the fancier 'aluminum' can not take that much pressure. Many have reported that they have replaced their Missions and other OEM tires with Dunlop and Michelin Rib type LT tires. In fact, some SOBs have come with such instead of the Missions, Hi-Run, etc. on them.

As a disclaimer - I'm not a tire guy any more (many many moons ago I worked for Firestone but that was in another era (pre-radials to be exact!!). My experience here is from doing the same -- I upgraded my axles last September (year ago) and had to change out all 5 wheels to accommodate the Goodyear 614s.
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Old 10-05-2008, 05:15 PM   #5
jjackflash
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Several members on this forum including myself have gone to Goodyear G14's with no problems.The newer wheels have been re certified to accept 110 psi.
As far as I know all Montana rims are 16x6 inch.
Jack
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Old 10-05-2008, 05:25 PM   #6
skypilot
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I was just trying to find an earlier post by, I believe bsmeaton. He corresponded with the makers of the wheels on our units and they had retested the wheels for Keystone (Montana) and had stickers to put on the wheels for 110 psi (original wheels are only rated to 80 psi). Can't find it right now but I know I read it in the past few days. May want to do some looking for it as well.

As I mentioned, several of us have upgraded to better tires. However, unless your wheels are rated and can handled the extra PSI, it is just too dangerous to run at 110 psi.
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Old 10-05-2008, 06:20 PM   #7
jjackflash
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Here ya go!
Jack
http://www.montanaowners.com/forums/...ad.php?t=30927
or
http://www.montanaowners.com/forums/...ad.php?t=28468
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Old 10-05-2008, 06:29 PM   #8
stiles watson
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I have the G614's on mine. My tire dealer certifies that the OEM Aluminum rims will handle the pressure. I now have 5,000 miles on the tires. In my opinion, when you make the change, you should insist on metal stems.
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Old 10-06-2008, 12:51 AM   #9
Glenn and Lorraine
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Quote:
quote:Originally posted by jeffwilliams1954

I need to know if I can put in place of my OEM Mission 235/80 R16 tires with the Goodyear 235/85/R16 G614RST tires. Does the 80 mean that it is a six inch rim? The Goodyear website says the G rated 235/85 needs a 6.5 inch rim. Any help would be great. Thanks
Jeff, I spent way too many years as a tire wholesaler/retailer. I mounted, balanced and serviced most every brand from the little tires you find on small trailers to the tires on the big 18 wheelers. I started part time in the business when the only construction was the old bias ply and left the business not that long ago. Actually You could say I never left as my Nephew now owns the same tire shop that his Dad and I started back in 1971. Enuff already....

Most every response above is petty much right on the money.
ggranch was close with his percentages. The 80 means the tires width is 80% of it's height. 85 means 85% of it's height and so on.
The G614s should work fine so long as the WHEELS can carry the load and air pressure ratings for these 10 ply tires. I would have your tire dealer dismount one tire and look for the load rating on the inside of the wheel before proceeding. Also be sure you get all tires balanced.
Metal valve stems shouldn't be an issue as ANY reputable tire dealer would NEVER mount any 6, 8 or 10 ply tires without them. If your dealer says you don't need them IMMEDIATELY cancel the deal go find another dealer.
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Old 10-06-2008, 02:38 AM   #10
exav8tr
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Well, while in Goshen I visited the Tredit Tire Companyin Elkhart. I spoke with Jennifer. Tredit does not make these wheels, only imports and distributes them, they are made by a company called Enkee. The OEM aluminum wheels that came with '07 and above Montanas were recertified for 110 psi or load rating of 3750 lbs, however, she stated that any year prior to '07 had not been recertified and advised against putting 110 psi in these wheels. I have the number to Enkee, somewhere I hope, and will be calling them when I can. Jennifer could not say, with any certainty, that the wheels were the same, although the numbers on mine match the later numbers. What is a guy to do?????
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Old 10-06-2008, 04:55 AM   #11
ols1932
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For what it's worth, some of the older Montanas, like ours, have 6-lug wheels. These wheels will not accept the the 110 psi. That information was obtained in a phone call with Treadit when I was desiring to put the G-rated tires on our rig. From what I have ascertained, the newer models of Montana, with 8-lug wheels may possibly withstand the 110 psi.

Orv
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Old 10-06-2008, 02:10 PM   #12
mail2us
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This may have been stated earlier or on another tire thread, but our 08 Montana 3400 RL rims, on the inside of them or back side have a sticker on them indicating they are 110 psi rated. FYI. Dennis
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Old 10-07-2008, 04:29 AM   #13
Waynem
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Please check your rims to see if they have the sticker. Pre-2007 and maybe some 2007's did not get the 7000 pound axle upgrade by keystone and may still have the old stamp.

Here are Keystone OEM rims that I replaced my tires.

A search on the forum for 110 psi, will get you some results.
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Old 10-13-2008, 06:26 AM   #14
sreigle
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Just be sure you also change out your spare tire. You do not want an 80 on one end of an axle and an 85 on the other. That can cause the axle to go out of alignment. We didn't have this situation but on an earlier Montana with D-rated tires I once bought a used E-rated tire in the same size so we could continue on down the road. After experiencing severe tire wear I talked with Keystone when we stopped at the service center and was informed having the different ratings on the same axle caused the problem. I went to an alignment shop and they agreed. Lesson learned.
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Old 10-15-2008, 02:08 AM   #15
dvanostran
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We have a 3485SA, 2008. Based upon everything I have been reading regarding the Mission tires (we have put about 13,000 miles on our new rig since Oct. of last year), I was really nervous about the Mission Tires. Last week went down and had 4 Goodyear 235/85/R16's installed. Even though everything I am reading and hearing, including the dealer telling me the aluminum wheels have been rerated to 110 lbs., I went to the Goodyear sight (www.goodyear.com) and there is an inflation table that will tell you the inflation levels depending on your weight. We had the unit weighed in Gillete, WY and know that the heaviest weight on the axle tires is 3100 lbs. According to the inflation table 85 lbs. in the G614 would be fine. I am running 95 lbs for a fluff factor. I now feel comfortable that the aluminum wheels will handle the 95 lb pressure even though re-rated for 110. Hope this helps someone.
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Old 10-15-2008, 02:35 AM   #16
Glenn and Lorraine
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Quote:
quote:According to the inflation table 85 lbs. in the G614 would be fine. I am running 95 lbs for a fluff factor. I now feel comfortable that the aluminum wheels will handle the 95 lb pressure even though re-rated for 110.
Dean,
What's a "fluff factor"?
Running any tire 10 PSI higher than recommended is not a good idea. Even an over inflated tire can heat up faster as there is less of a foot print on the road. As there is less foot print on the road the tires will wear down the middle rather than evenly across. Also with less foot print you also have less friction when breaking. I would seriously reconsider as over inflation can sometimes be more dangerous than under inflation.
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Old 10-15-2008, 02:58 AM   #17
Delaine and Lindy
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We have had 3 5th wheels with the G614's and run them at 105 to 110 lbs per tire. Don't understand why you would run them so low, if your rims are rated for 110 G rated tires. Well thats what I would run. Anytime you run low air pressure it causes heat in the tire and you don't want that. You will for sure have a tire failure. A proper air pressue will let the tire roll much better and that will get you better fuel mileage. I do the same with my Truck tires, what ever the side wall says thats what I run. Tires run cooler when the inflations is correct. Some people will lower pressure when not towing, I never change my tire pressure. I also run the Pressure Pro System and have instant monitoring on all tires. Lower air pressure to get a better ride isn't a problem with my Truck, my Truck rides fine, its a HD Truck. I also admit I do tow heavy. GBY.....
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Old 10-15-2008, 03:34 AM   #18
LonnieB
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Thank you Dean, for bringing something up that I have been trying to get across for a long time.

The maximum inflation on ANY tire means just that, MAXIMUM. It does NOT mean the tire requires that maximum amount, just that the tire will safely withstand that amount.

Every tire has a maximum load, and maximum speed rating molded into the sidewall. The maximum load, maximum speed, and maximum psi, are all relative to each other. If the actual load on the tire is less than the maximum the tire is rated for, it won't require the maximum inflation to operate safely.

The only way to accurately determine the correct amount of air pressure required, is to weigh the trailer when fully loaded, and adjust according to a load/inflation table.

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Old 10-15-2008, 05:15 AM   #19
bsmeaton
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Just something I noticed - when using the Goodyear inflation table, inflating the G-series tires to 80psi gives you exactly the same load rating as the E-series tires at 80psi (3,042 lbs). There is no real advantage to the G-series over E-series tires if you are running no more 3,042 lbs per tire load or have 6K axles.

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Old 10-15-2008, 05:55 AM   #20
skypilot
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This goes back and is along the same lines as an earlier discussion about trailer weights and axles. The tires, wheels, axles are all vitally important in getting us down the road safely. Dean mentioned 'fluff factor' in his post above, I happen to agree that the G rated tire gives a little extra cushion before we exceed its max carrying capability. With an 'E' rated tire, I feel (and this is a personal opinion) we are at, or extremely close to, the maximum carrying capability of that tire all the time (just like we are with 5.7K axles). If we experience any type of abnormal loading (heavy cross-wind, high crown, even unique loading of the trailer for a particular trip), we could theoretically exceed the limits on the tires and / or axles. By having G rated tires, aired to 90 or 100 lbs we gain several hundred pounds of additional weight carrying capability to handle those exceptions. It doesn't modify the certified carrying weights, just gives us a cushion should we experience something out of the norm.

I realize there are thousands, possibly tens of thousands, of trailers out on the highways running E rated tires and 5.7 or 6K axles. But upgraded tires (or axles) are just like insurance, you hope you never need to use it but when you do, then insurance is a good thing.
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