Improving Ride Quality
New User
Joined: Jun 2016
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Whether or not a person would 'get caught' is irrelevant regarding the statement that installing tires having a lesser load rating is illegal. If it is actually illegal to do so, it should be a pretty easy task to provide some documentation of that. That's what I'm looking for.
https://www.fmcsa.dot.gov/regulation...section/393.75
(f) Tire loading restrictions (except on manufactured homes). No motor vehicle (except manufactured homes, which are governed by paragraph (g) of this section) shall be operated with tires that carry a weight greater than that marked on the sidewall of the tire or, in the absence of such a marking, a weight greater than that specified for the tires in any of the publications of any of the organizations listed in Federal Motor Vehicle Safety Standard No. 119 (49 CFR 571.119, S5.1(b)) unless:
(1) The vehicle is being operated under the terms of a special permit issued by the State; and
(2) The vehicle is being operated at a reduced speed to compensate for the tire loading in excess of the manufacturer's rated capacity for the tire. In no case shall the speed exceed 80 km/hr (50 mph).
(1) The vehicle is being operated under the terms of a special permit issued by the State; and
(2) The vehicle is being operated at a reduced speed to compensate for the tire loading in excess of the manufacturer's rated capacity for the tire. In no case shall the speed exceed 80 km/hr (50 mph).
Tuned
Joined: May 2010
Posts: 434
Likes: 23
From: Somewhere in Alaska
Found this information online:
https://www.fmcsa.dot.gov/regulation...section/393.75
https://www.fmcsa.dot.gov/regulation...section/393.75
New User
Joined: Jun 2016
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Found more documentation for all vehicles under the National Traffic and Motor Vehicle Safety Act:
eCFR ? Code of Federal Regulations
S5.1.2 Except in the case of a vehicle which has a speed attainable in 3.2 kilometers of 80 kilometers per hour or less, 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 by 49 CFR part 567. Except in the case of a vehicle which has a speed attainable in 2 miles of 50 mph or less, 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 by 49 CFR part 567. If the certification label shows more than one GAWR for the axle system, the sum shall be not less than the GAWR corresponding to the size designation of the tires fitted to the axle. If the size designation of the tires fitted to the axle does not appear on the certification label, the sum shall be not less than the lowest GAWR appearing on the label. When a passenger car tire is installed on a multipurpose passenger vehicle, truck, bus, or trailer, the tire's load rating shall be reduced by dividing by 1.10 before calculating the sum (i.e., the sum of the load ratings of the tires on each axle, when the tires' load carrying capacity at the recommended tire cold inflation pressure is reduced by dividing by 1.10, must be appropriate for the GAWR).
Tuned
Joined: May 2010
Posts: 434
Likes: 23
From: Somewhere in Alaska
Not exactly... It's for vehicles over 10k gvwr (and RV trailers). But, I'll concede that it may apply to some Superduty's.
That's true. The total weight capacity of the tires on an axle (for vehicles over 10k gvwr) must be higher than the load rating of that axle. Still doesn't say it's illegal to install tires with lower weight rating. Am I splitting hairs? Maybe.
This is saying unless your vehicle can only reach a speed of 50 mph (80 kmh), the tires have to be rated to at least the axle's gross weight rating (GAWR).
Last edited by ak-angler; Jun 24, 2016 at 03:58 PM. Reason: Clarification of poorly written sentence.
New User
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truck jumpd sideways over bumps? [Archive] - Dakota Durango Forum
Cargo Master
Joined: Jan 2012
Posts: 3,053
Likes: 21
From: Pittsburgh, PA
I believe they jump more if the shocks have a very stiff compression stroke. It is also a characteristic of stock leaf springs because their spring rate is so high and a light rear end.
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Tuned
Joined: Jun 2015
Posts: 344
Likes: 7
Case in point: Your FX4 has an LSD (I presume) and bounces to the right. My dad's Silverado Z71 has and LSD and bounces...not sure which direction, but it definitely bounced sideways in the rear and was pretty bad on the stock tires. A tire change did help, but on bad washboards, it definitely still goes sideways - sometimes enough to make the traction control perk up a bit. My open diff F-250 has never once bounced sideways back there. Now, sometimes it'll buck you up out of your seat like a bronco, but it never goes sideways. That's one of my primary reasons I'm thinking to go selectable locker instead of dropping in an LSD. LSD's just seem to bounce funny. Again - not sure if that's a law of the universe or anything - just something I've noticed in my experience.
Junior User
Joined: Aug 2011
Posts: 99
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I don't know if this is particularly true or not, but it seems that trucks with an open diff mostly just bounce more up and down over bumps in the rear where trucks with an LSD in the back bounce around sideways a lot more over the same bumps. Seems like all of the LSD trucks I've driven have been much more squirrely on the same washboards and dirt roads than similar pickups with an open diff.
Case in point: Your FX4 has an LSD (I presume) and bounces to the right. My dad's Silverado Z71 has and LSD and bounces...not sure which direction, but it definitely bounced sideways in the rear and was pretty bad on the stock tires. A tire change did help, but on bad washboards, it definitely still goes sideways - sometimes enough to make the traction control perk up a bit. My open diff F-250 has never once bounced sideways back there. Now, sometimes it'll buck you up out of your seat like a bronco, but it never goes sideways. That's one of my primary reasons I'm thinking to go selectable locker instead of dropping in an LSD. LSD's just seem to bounce funny. Again - not sure if that's a law of the universe or anything - just something I've noticed in my experience.
Case in point: Your FX4 has an LSD (I presume) and bounces to the right. My dad's Silverado Z71 has and LSD and bounces...not sure which direction, but it definitely bounced sideways in the rear and was pretty bad on the stock tires. A tire change did help, but on bad washboards, it definitely still goes sideways - sometimes enough to make the traction control perk up a bit. My open diff F-250 has never once bounced sideways back there. Now, sometimes it'll buck you up out of your seat like a bronco, but it never goes sideways. That's one of my primary reasons I'm thinking to go selectable locker instead of dropping in an LSD. LSD's just seem to bounce funny. Again - not sure if that's a law of the universe or anything - just something I've noticed in my experience.
Elder User
Joined: Jun 2014
Posts: 932
Likes: 10
From: Tampa
Not exactly... It's for vehicles over 10k gvwr (and RV trailers). But, I'll concede that it may apply to some Superduty's.
That's true. The total weight capacity of the tires on an axle (for vehicles over 10k gvwr) must be higher than the load rating of that axle. Still doesn't say it's illegal to install tires with lower weight rating. Am I splitting hairs? Maybe.
That's true. The total weight capacity of the tires on an axle (for vehicles over 10k gvwr) must be higher than the load rating of that axle. Still doesn't say it's illegal to install tires with lower weight rating. Am I splitting hairs? Maybe.
If..by any chance you are carrying/towing at your vehicle's original GVW rating and..you are involved in any incident where your cargo was a factor in any manor and .. if an accident investigator finds your vehicle not to be in compliance with the manufactures minimum tire rating it CAN become a citable and an at fault offense.
And .. it scares me to think anyone would be STUPID enough to challenge the legality of such
Logistics Pro
Joined: Jan 2010
Posts: 3,554
Likes: 6
From: Mesick
Let me re-phrase may comment about the legality of replacing your tires with tires with a lesser rating that originally required by the manufacture.
If..by any chance you are carrying/towing at your vehicle's original GVW rating and..you are involved in any incident where your cargo was a factor in any manor and .. if an accident investigator finds your vehicle not to be in compliance with the manufactures minimum tire rating it CAN become a citable and an at fault offense.
And .. it scares me to think anyone would be STUPID enough to challenge the legality of such
If..by any chance you are carrying/towing at your vehicle's original GVW rating and..you are involved in any incident where your cargo was a factor in any manor and .. if an accident investigator finds your vehicle not to be in compliance with the manufactures minimum tire rating it CAN become a citable and an at fault offense.
And .. it scares me to think anyone would be STUPID enough to challenge the legality of such
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