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On my Ford E 450 Super Duty Class C RV Chassis I have Firestone so called "10 Ply" Load Range E Tires on the rear duals LT 225 75 X R16. I think LT 235 75 X R16 may still fit ????

Just had the Smart Weigh performed at Escapees RV Park in Livingston and I'm a bit overweight in the rear so wondered do they make a so called "12 Ply" hopefully higher load rated tire (F maybe ???) in the LT 225 75  X 16 or LT 235 75 X 16 that will still fit my duals and give me a bit more weight rating???????????

Thanks in advance, best wishes n God Bless all here

John T

Edited by oldjohnt

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There is a tire size calculator that will help you determine alternate size tires. Usually places like Discount Tire, etc. can help you with that as well. Once you determine a viable alternate size then you will be better able to search for a tire that does what you want. 

The calculator can be found here.

Edited by Chalkie
added text

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8 hours ago, oldjohnt said:

that will still fit my duals and give me a bit more weight rating???????????

As an engineer, I find it strange to see a need to address weight ratings and any attempt to increase these ratings.....   :huh:   I'll not even bother other than to tell other readers that there is a long list of validated reasons why the solution to this is not in different tires but in lower rear axle weight! 

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Load Range E, is targeted to a various weight level. 

From my research 10-12 years ago with a 16" wheel, Load Range E was the highest Load Range available. 

The sad reality is, that many manufactures build RV's (A general statement, not just targeted to Class C.), that are basically 'at' capacity, or very close to 'capacity' when they leave the factory. And shame on DOT for letting these roll out as certified ... A few, have had front end's overweight as they rolled off the factory floor. (More Class A's then C's - from what I understand(?). Evidenced by some recalling units and upgrading front ends.). 

Anyway's, you did the right thing by getting an actual Four Corner's Weight. Now you need to look at what you can do. 

-Move weight around to shift more to the front

-Go on a diet? (Class C wise:)!)

-Get PSI up to the max level's for your specific tire and rim combo

And as other's provide more input. If you, or they, do find that higher Load Ratings of tires are available in an appropriate size for you unit, great. But, as Kirk pointed out, it's more then just the weight that tires can hold - it's a total engineered package. Looking into suspension modifications for the problem Rear Area, may also be prudent. 

Be safe, have fun, and good luck,

Smitty

 

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Do not go over rear axle and king pin rating/axle ratings etc for tow vehicle. Frame is probably close to maxed out at axle rating. We do have 13,000 pound capacity on tires but 10,600 pounds as combination of the axles. Putting on heavier rated axles and springs still puts overload on frame.

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If you go to a 12 ply tire, the truck will ride rough and hard and you may now exceed your spring load design. Look at the door sticker, the suggested tire pressure is probably 65 psi vs the max tire pressure of 80 psi. The best you could do is run the max tire pressure which would result in a somewhat rougher ride.

 

Greg

Edited by gjhunter01

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10 hours ago, oldjohnt said:

On my  RV I'm a bit overweight

 

John I edited your statement to be what many RV owners have stated included me with a DRV fifth wheel.

Smitty77_7 said is a shame that DOT lets them roll out.  I have been (verbally) informed that with the components I have a higher GVW could have placed on my RV. Also I have been told it's impossible to recertify even with a $10.000 upgrade.

I only know of one re certify and that was a E250 to a E250HD and that was a Ford dealer before the dealer could complete sale . 

Clay DRV MS 38PS3

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14 hours ago, Kirk Wood said:

As an engineer, I find it strange to see a need to address weight ratings and any attempt to increase these ratings

 Thanks Kirk, HOWEVER as I stated I'm an ELECTRICAL engineer NOT Mechanical or Tire expert, but still being safety conscious, sure I am concerned with ALL ratings (tires, springs, axles, wheels, frame). I just didn't study tires which is why I came to you experienced gents seeking advice, and believed for starters there may be a TIRE I could use that has higher weight capacity for added safety, even if there are other issues, BUT YOU CAN BET I WILL LOOK AT THAT ALSO LOL.  I am indeed  concerned with ANY AND ALL  improvements that will increase safety, even if tires are ONLY the start and confident I can find help here. I didn't weigh all that much over and a diet and re distribution may bring me within specs, but I prefer to be OVER SAFE on tires as well as all other issues I may be able to cure while I'm still in Texas..............

NOTE I did get a tip Goodyear may have tires that will still fit and  have a higher weight rating ?? Better safe then sorry and no problem in added tire capacity even if other issues exist.

 THANKS FOR THE HELP KIRK maybe this winter we can meet up as we discussed previously, sure would be fun

John T  (Currently in your State in Austin)

 

Edited by oldjohnt

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12 hours ago, Smitty77_7 said:

The sad reality is, that many manufactures build RV's (A general statement, not just targeted to Class C.), that are basically 'at' capacity, or very close to 'capacity' when they leave the factory. And shame on DOT for letting these roll out as certified ... A few, have had front end's overweight as they rolled off the factory floor. (More Class A's then C's - from what I understand(?). Evidenced by some recalling units and upgrading front ends.). 

Anyway's, you did the right thing by getting an actual Four Corner's Weight. Now you need to look at what you can do. 

-Move weight around to shift more to the front

-Go on a diet? (Class C wise:)!)

-Get PSI up to the max level's for your specific tire and rim combo

THANKS SMITTY

Ever since Escapees Smart Weigh I'm indeed looking into ALL you advised and already started the procedure.

Thanks again

Best wishes n God Bless

John T

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12 hours ago, gjhunter01 said:

The best you could do is run the max tire pressure which would result in a somewhat rougher ride.

Thanks Hunter, I ALREADY run at the Max Load at X  PSI and may check out some Goodyear Tires which have a higher rating in addition to all the other great advice above, I knew I would get good advice here THANKS TO ALL.........

 

Best wishes n God Bless

 

John T

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14 hours ago, oldjohnt said:

On my Ford E 450 Super Duty Class C RV Chassis I have Firestone so called "10 Ply" Load Range E Tires on the rear duals LT 225 75 X R16. I think LT 235 75 X R16 may still fit ????

Just had the Smart Weigh performed at Escapees RV Park in Livingston and I'm a bit overweight in the rear so wondered do they make a so called "12 Ply" hopefully higher load rated tire (F maybe ???) in the LT 225 75  X 16 or LT 235 75 X 16 that will still fit my duals and give me a bit more weight rating???????????

Thanks in advance, best wishes n God Bless all here

John T

I,m kinda wondering why your 450 is running the smaller tire My dodge 3500 has LT235/85R16 and its a dually

 

Edited by Devilishjim

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Just now, Devilishjim said:

I,m kinda wondering why your 450 is running the smaller tire My dodge 3500 has LT235/85R16

 Jim, I kinda wonder that myself (size tire that what was on when I purchased it used) and one reason I'm looking into replacement higher rated tires as well as all other possible upgrades for more safety.

Thank you,

 John T  

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22 hours ago, Chalkie said:

There is a tire size calculator that will help you determine alternate size tires. Usually places like Discount Tire, etc. can help you with that as well. Once you determine a viable alternate size then you will be better able to search for a tire that does what you want. 

The calculator can be found here.

I went back and looked at that link (it was one in my bookmarks) and it seems they have changed what it does. It used to have a visual component which helped out. So I went on the hunt and here is a better calculator I think.

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Chalkie, yep that latest link seems to work THANKS

If I can find tires that still fit but have a higher rating I plan to purchase them just for an added margin of safety over my current tires BETTER OVER SAFE THEN SORRY is my plan as far as TIRES are concerned, and if I can find more ways to improve safety and ratings regarding weight, I'M ALL IN................  

 

Thanks to all for the great advice

 

John T

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Okay, I'm showing my age here, but... Back in the day I had an F350 with a 48' trailer, also on Ford rims. Ford rims at that time did not have enough offset to run 235/245 tires. They would touch at the widest part of the tire and rub. The practical limit was 215's. Surely they've fixed that by now, but one might want to check before they spend..

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1 hour ago, Jaydrvr said:

Ford rims at that time did not have enough offset to run 235/245 tires. They would touch at the widest part of the tire and rub.

Thanks Jay, INDEED I recall the same thing from my past and that's why I asked the question of the tire experts (I'm NOT any tire expert or mechanical engineer, but still very safety minded)  and plan to do more research on what IF ANY tires will still "properly" fit my current rims yet have a higher load rating just to improve my overall safety. If a "diet" and weight redistribution cant bring me within specs, I will study other mechanical upgrades (if any exist) but regardless, I just feel safer with the highest tire ratings reasonably feasible. There are THOUSANDS of Ford Super Duty E 450 Class C's out there, many of which are longer and heavier then mine, which have 16 inch tires and wheels so I'm just shopping for any tires that STILL FIT AND WORK but exceed my 10 Ply Load Range E 80 PSI current tires.......... 

Great info above, THANKS ALL

PS After I do my research and make some changes, Escapees Smart Weigh will give me a re weigh for only 25 bucks yayyyyyyyyy

John T

Edited by oldjohnt

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10 hours ago, oldjohnt said:

 Jim, I kinda wonder that myself (size tire that what was on when I purchased it used) and one reason I'm looking into replacement higher rated tires as well as all other possible upgrades for more safety.

Thank you,

 John T  

Whats the tag inside the door show for tire size ?

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If you upgrade to a tire with higher pressure make sure your rims are rated for the higher pressure.

Lenp

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On ‎11‎/‎4‎/‎2017 at 7:16 PM, Devilishjim said:
On ‎11‎/‎4‎/‎2017 at 9:12 AM, oldjohnt said:

 

Whats the tag inside the door show for tire size ?

  Jim, on the door it calls for LT 225 75 x R16 at 80 PSI Cold AND THATS WHAT I HAVE Load Range E and as I said that's what I see on many Class C's even longer and heavier then my coach. I just want to research to see if there's any tires of the same size (or a size that still fits my wheels and duals) but which have a higher load rating like F or more. Even if I trim my weight down within spec I just don't like to operate close to the edge, thus my post here seeking information.

 

On ‎11‎/‎4‎/‎2017 at 7:37 PM, lenp said:

If you upgrade to a tire with higher pressure make sure your rims are rated for the higher pressure.

Lenp

 Indeed Lenp, thanks. So often when you try to upgrade one component then another rears its head so I will look into what you mentioned.   

 

 THANKS TO ALL FOR THE TIRE ADVICE AS WELL AS OTHER INFORMATION.........

 

John T 

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Hi John! Here are some hot links to what I think will be helpful information with your situation:

Dual tire spacing explanation

16" load range G tires are only made in 235/80R16: http://www.sailuntires.ca/MRT/S637.html As you see, this may require upgrading to different rims, which affects dual tire spacing. Goodyear also makes this tire.

Another option is upgrading to 17.5" rims and tires, = very expensive. Another option would be to have a used  3rd member from a E550 installed.

There is a company that sells dual spacers, machined from billet steel to enable wider tire spacing and larger load range G tires, if there is room in wheel well. A possible issue with these is; the engineers design a particular dually setup with the wheel bearing in mind, moving the center of the duals away from the bearing center line reduces bearing life and load capacity.

I guess what I'm trying to say is, the best possible solution is to reduce your rear gross axle weight to conform to its maximum load rating.

 

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Thanks Good Neighbor Ray, that was an excellent article regarding dual wheels. So far I haven't found LT 225 75 R 16 (10  Ply Max load at 80 PSI cold) higher then Load Range E which is what I already have grrrrrrrrrrrrrrrr and it appears a 235 would  be too wide on my present wheels and spacings. I'm just at the edge of the weight rating and a diet may get me in specs HOWEVER I just don't like to travel so close to safetys  edge and would prefer some wiggle room and a higher load rated tire IF ANY WERE MADE THAT STILL FIT PROPERLY.

 

 John T  

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Hi John T -

You want to look at the tire's load index number for actual capacity. 116, 121, 126, and so on. One of The Great Mysteries of tire lookin in the web is it is pretty much impossible to search by load index..

Also I read somewhere "LT" tires are designed to work at 100% load rating 100% duty cycle. 

Me likes a 20% capacity cushion or so but I have zero credentials to back that up scientific wise. 

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29 minutes ago, noteven said:

Me likes a 20% capacity cushion or so but I have zero credentials to back that up scientific wise. 

Not even, AMEN TO  THAT. I don't like living on the edge of safety recommendations, the reason I posed this tire question here.

I have studied those 116 to 126 numbers also but NOT figured it out grrrrrrrrrrrrrrrr and a call to a tire dealer drew the deer in the headlight (ears) response.   I haven't given up yet and if I ever get a real technical answer I will let yall know. Tires DO HAVE the Max Load at X PSI right on the sidewalls (for duals or single) and several brands of Load Range E I've looked at so far are real close to the same numbers, Michelin was a few pounds heavier then Firestone or Goodyear FWIW.

John T Live from Austin Texas

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