Good Sam Club Open Roads Forum: 18" tire question - ANOTHER UPDATE
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 > 18" tire question - ANOTHER UPDATE

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specta

utah

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Posted: 08/15/21 05:18pm Link  |  Quote  |  Print  |  Notify Moderator

19.5s were never even a consideration for me.

Not something I would ever need.


Kenny
2011 Chevy 2500 HD 6.0L 4wd
1995 Lance 945 Onan QG 2500 LP
Regular cab. The best looking trucks.


NRALIFR

Truck Camping Out West

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Posted: 08/15/21 06:15pm Link  |  Quote  |  Print  |  Notify Moderator

I never liked the idea of putting 19.5’s on any vehicle that wasn’t designed for them. As Siletzspey said, they are considerably heavier, and will cause problems with more than just the tire hoist. The increase in “unsprung weight” makes your springs and shocks less effective. The higher rotating mass makes your brakes less effective.

They aren’t quite the “upgrade” they used to be for heavy TC haulers now that the larger wheel sizes are available, and a range of tire options to mount on them. They’re what I wanted but they aren’t for everyone. The F450 pickups (2008-2010 and 2015-current) all come with them, and the suspension and brakes to handle them.

But, there are some M+S 19.5’s available. Continental makes a few (Conti Scandinavia and Conti Hybrid). There’s even a few 19.5’s with the “Three Peak Mountain Snowflake” symbol on them. I hope I never need any of those. [emoticon]

[emoticon][emoticon]


2001 Lance 1121 on a 2016 F450 ‘Scuse me while I whinge.
And for all you Scooby-Doo and Yosemite Sam types………..Let’s Go Brandon!!!


ticki2

NH

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Posted: 08/15/21 06:16pm Link  |  Quote  |  Print  |  Notify Moderator

Siletzspey wrote:

My 2015 F350 SRW 4x4 came with LT275/70R18 tires rated at 3640-lbs, and the wheels (rims) are rated for 3590-lbs. Ford publishes a spec book, and if you can find it via Googling,


That’s the first I’ve heard of something published where the oem wheels were rated less than the oem tires . Interesting.


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d3500ram

Colorado

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Posted: 08/15/21 06:39pm Link  |  Quote  |  Print  |  Notify Moderator

Years ago I acquired a camper loading diagram manual... not sure if that data had any tire info (I do not recall.) But, as mentioned here and and as I reiterate, wheels will not (as far as I can tell) will not be rated for any lower weight capacity than any tire offered from the factory on that exact rim. Corporate lawyers will never allow that to happen.

If a 2500 truck, for example, had a the same tire/rim on a factory offering and that same tire/rim and tire combo was offered on a 3500 (for the same wheel) we can be assume that the wheel has the higher weight capacity of the 3500 irrespective of axle rating or GVRW. Wordstuff aside, a rim-tire rating has to match at least that which the tire is capable of.

From my understanding, no truck manufacturer has ever stamped nor published a weight rating on or for their factory wheels. All we can do is assume that they will never issue a product for less than the tire that was around it regardless of the model on which it is sold.

NRALIFR

Truck Camping Out West

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Posted: 08/15/21 07:06pm Link  |  Quote  |  Print  |  Notify Moderator

ticki2 wrote:

Siletzspey wrote:

My 2015 F350 SRW 4x4 came with LT275/70R18 tires rated at 3640-lbs, and the wheels (rims) are rated for 3590-lbs. Ford publishes a spec book, and if you can find it via Googling,


That’s the first I’ve heard of something published where the oem wheels were rated less than the oem tires . Interesting.


Since Ford doesn’t actually make the wheels, I would consider that “rating” to be in the same category as their axle ratings, which are typically derated from the axle manufacturer’s rating.

My tire inflation sticker doesn’t call for the tires to be inflated to 110 psi. It specs ~90 front and 85 rear. That effectively derates the max load capacity for each tire.

[emoticon][emoticon]

d3500ram

Colorado

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Posted: 08/15/21 07:26pm Link  |  Quote  |  Print  |  Notify Moderator

NRALIFR wrote:

....

Since Ford doesn’t actually make the wheels, I would consider that “rating” to be in the same category as their axle ratings, which are typically derated from the axle manufacturer’s rating.
....

Interesting opinion, but wouldn't it be more depended on the tire (for the wheel itself) as opposed to axle?

Not saying you are incorect, only saying that the Corporate Layers would never allow for any "weakest link" being less than any other "Brand" rating or number... That is, a "Dodge" or "Ford" layer would never allow a wheel to be rated lower than a "Goodyear" product on which it was mounted to a Dodge or Chevy wheel.

NRALIFR

Truck Camping Out West

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Posted: 08/15/21 07:42pm Link  |  Quote  |  Print  |  Notify Moderator

I’m actually agreeing with you.

I think it’s highly unlikely that any OEM would mount a tire with “ Max Loaded Inflation-Single (LB) 3970/110” stamped on its sidewall on a wheel that was rated less in lbs or psi.

I think the numbers cited from the Ford specs book are simply Ford’s ratings/specs for how they are using them, at Ford’s specified inflation pressure.

Similarly, Ford’s rating for the Dana S110 rear axle on my truck is significantly lower than what Dana rates the axle for.

[emoticon][emoticon]

* This post was edited 08/15/21 10:07pm by NRALIFR *

Siletzspey

Shedd, OR

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Posted: 08/15/21 10:51pm Link  |  Quote  |  Print  |  Notify Moderator

Google "Ford super duty truck source book". Long ago I found a PDF of the "source book" for my 2015 F350, which is where I got the 3590-lb wheel rating and 3640-lb tire rating.

While talking with a local Les Schwab tire center, they said Ford/Dodge/etc "OEM" wheels tend to be honestly rated and robust, and most of the wheel failures they see are with 3rd party wheels where the ratings are suspect. When telling them I was at ~95% of wheel and tire capacity, they said I was fine, but if I was still inclined to worry and upgrade something, I should focus on the tires first.

As NRALIFR notes, Ford seems to under-spec the axle ratings, so I don't worry about being at 7K on 7K rated axles.

mbloof

Beaverton, OR

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Posted: 08/16/21 07:06am Link  |  Quote  |  Print  |  Notify Moderator

While the selection of available 19.5" tires is not as good as consumer sizes, there are a number of "MT+Snowflake" winter rated tires available.

I made the switch years ago with my 1997 Ford F250HD. OEM outfitted with (what?) 16" tires/rims it was a nobrainer to go to better rated 19.5" tires/rims.

Sure they are heavier (and the ones I have are just as wide) as the stock sized tires. Sure the size I picked led me to change the speedodmeter setting for more accurate speed. Not that I've ever noticed the weight - I've never changed one or had any 'ride issues' from their use.

They have for the most part been a ride improvement as the reduced sidewall flex helped greatly with truck/camper sway. So much so that when I eventually replaced the truck with a 2017 and did a ~100mile test drive with the 18" OEM tires/rims installed on it afterwards I moved the 19.5" tires/rims from the old truck to the new one.

While surely not for everyone and there are other options available however switching to 19.5" Toyo class "G" tires and Vision Heavy Hauler rims works well for me.


- Mark0.

JIMNLIN

Oklahoma

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Posted: 08/16/21 07:40am Link  |  Quote  |  Print  |  Notify Moderator

Fleet Ford Specs websites still shows 18"/20" wheels at 3590 lbs capacity..

Tire and rim selections has been the same for decades per FMVSS 571.110/120 for under 10k and over 10k vehicles.
And says ...S5.1 Tire and rim selection.
...***the sum of the maximum load ratings of the tires fitted to an axle shall be not less than the gross axle weight rating (GAWR) of the axle system as specified on the vehicle's certification label required ....***
snipped for length.

I've seen OEM tires capacity well above the vehicles GAWRs or the wheel ratings over the years.

Rawr includes the lessor of the vehicle mfg (not axle mfg) tires/wheels/rear spring pack/axle assy.
Increasing tire capacity gives you more tire reserve capacity. If we want more load carrying capacity the wheels/rear suspension may have to have a increase also.


"good judgment comes from experience, and a lot of that comes from bad judgment" ............ Will Rogers

'03 2500 QC Dodge/Cummins HO 3.73 6 speed manual Jacobs Westach
'97 Park Avanue 28' 5er 11200 two slides

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