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  1. #1
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    Axle vs Tire rating Q

    Wow... first of all these forums have been incredibly helpful, so thank you to all those that post. One of the most informative places I have found while researching, and is making our search for a 5th wheel so much more comprehensive.

    So the question... have read so many of the SRW vs DRW "debates" in just about every thread in here. One thing I didn't see a lot of information on was related to tire and axle ratings. My Ram 3500 has a GAWR in the rear of 7000lbs. However, my tires are at 3195 each. Am I interpreting this correctly... that my tires are the "weak point" if I had 6500 back there? (Seeing that my current tires would only be rated to 6190.) I don't plan on throwing that kind of weight back there, but for learning sake... I am trying to see if I need to get better tires to more closely match my axle rating.

    Now... next level of this question... if a rear axle on a 3500 DRW has a rating of 9750, what accounts for that big of a difference from the SRW? I only saw one post (but could have missed others) that talked about a slight difference between the two axles. If I remember correctly, it is slightly longer and the end of it was a little wider? Anyway...I might take this Q to the Ram forums (say a prayer for me)... but thinking long term here, the people that throw on "super singles" instead of dually's... is it just about finding a better tire or is the axle in dually's really that much different?

    A lot to unpack there... sorry for the length of the post.
    ---~-~-~-~-~-~---
    351M & 2018 Ram 3500 SRW

  2. #2
    Paid my dues 😁 FT4NOW's Avatar
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    Welcome to the forum. I'm sure you'll get a lot of responses to your questions on this one. Even staying with a SRW, there are better tire choices. If I recall, I have Michelin tires that are a little over 3800lbs each in capacity. Also consider some tires have different ratings in a dual vs single setup. Whatever route you go, SRW or DRW, make sure you get some good LT tires. Ideally, the tires shouldn't be the weak point in your setup.

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  3. #3
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    Quote Originally Posted by FT4NOW View Post
    Welcome to the forum. I'm sure you'll get a lot of responses to your questions on this one. Even staying with a SRW, there are better tire choices. If I recall, I have Michelin tires that are a little over 3800lbs each in capacity. Also consider some tires have different ratings in a dual vs single setup. Whatever route you go, SRW or DRW, make sure you get some good LT tires. Ideally, the tires shouldn't be the weak point in your setup.

    Sent from my SM-G950U using Tapatalk
    Solid, thanks for the reply. I thought they seemed a little low... FWIW I have the Mazama Open Range (Load Range 121 - 3195lbs). Needless to say I won't buy them again.
    ---~-~-~-~-~-~---
    351M & 2018 Ram 3500 SRW

  4. #4
    Long Hauler geotex1's Avatar
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    Depending on which RAM forum, you might get good information. The other 85%... If the responder cannot think in 3 dimensions and never had a class discussing free body diagrams, the information received should be considered mob knowledge akin to heresay.

    Keep it simple:

    Consider GAWR the breaking load. Fundamentally, that is what it is, BUT realize that AWR is RARELY governed by the pumkin/innards/tubes/shaft but frequently what suspends the axle. Your tires are the limiting factor. Couple load range F offerings out there, but likely not fitting the RAM.

    SRW - 2 points of support. DRW - 4 points of support - load sharing/spreading.
    Rob & Nikki + Cloverfield
    2020 Grand Design Solitude S-Class 3350RL
    2015 RAM 3500 Longhorn Laramie Crew Cab, Long Bed, 4x4 Dually Cummins/AISIN

    Mountains of Pennsylvania

  5. #5
    Rolling Along
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    Quote Originally Posted by NWbulldog View Post
    Wow... first of all these forums have been incredibly helpful, so thank you to all those that post. One of the most informative places I have found while researching, and is making our search for a 5th wheel so much more comprehensive.

    So the question... have read so many of the SRW vs DRW "debates" in just about every thread in here. One thing I didn't see a lot of information on was related to tire and axle ratings. My Ram 3500 has a GAWR in the rear of 7000lbs. However, my tires are at 3195 each. Am I interpreting this correctly... that my tires are the "weak point" if I had 6500 back there? (Seeing that my current tires would only be rated to 6190.) I don't plan on throwing that kind of weight back there, but for learning sake... I am trying to see if I need to get better tires to more closely match my axle rating.

    Now... next level of this question... if a rear axle on a 3500 DRW has a rating of 9750, what accounts for that big of a difference from the SRW? I only saw one post (but could have missed others) that talked about a slight difference between the two axles. If I remember correctly, it is slightly longer and the end of it was a little wider? Anyway...I might take this Q to the Ram forums (say a prayer for me)... but thinking long term here, the people that throw on "super singles" instead of dually's... is it just about finding a better tire or is the axle in dually's really that much different?

    A lot to unpack there... sorry for the length of the post.

    FWIW, the DOT (in some jurisdictions) will simply add up your tire capacities to determine if you’re overweight.

  6. #6
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    Quote Originally Posted by geotex1 View Post
    Depending on which RAM forum, you might get good information. The other 85%... If the responder cannot think in 3 dimensions and never had a class discussing free body diagrams, the information received should be considered mob knowledge akin to heresay.

    Keep it simple:

    Consider GAWR the breaking load. Fundamentally, that is what it is, BUT realize that AWR is RARELY governed by the pumkin/innards/tubes/shaft but frequently what suspends the axle. Your tires are the limiting factor. Couple load range F offerings out there, but likely not fitting the RAM.

    SRW - 2 points of support. DRW - 4 points of support - load sharing/spreading.
    HA! Thanks for this, makes sense. I've seen some of those forums/posts you speak of... especially the "super single" conversation...
    ---~-~-~-~-~-~---
    351M & 2018 Ram 3500 SRW

  7. #7
    Site Team xrated's Avatar
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    Your tire should NEVER be the weak spot on the truck. A SRW truck with a 7000 lb axle weight rating should have tires that are rated OVER the GAWR of the respective axle. The order of progression on a truck should be as follows.
    1. Add weight until you have reached the available payload of the truck. ( GVWR - actual weight of the truck = available payload.
    2. Once you reach that point, you are at the GVWR of the truck. Any further addition of weight will put you not only over the payload number, but obviously, over the GVWR of the truck.
    3 Next in line, if you keep adding weight to the truck, is the axle weight rating.
    4. After that has happened, if you keep adding weight, you will eventually reach the tire load capacity rating.

    If you exceed all of that, make sure your life insurance is fully paid.......LOL.....seriously though, just don't ever get to the point that you have exceeded the available payload, and you won't have to worry about the other capacities, unless you have never maintained the truck or your tires are not the correct ones, or the correct tires are totally shot and wouldn't have anywhere near their rated load capacity at the sidewall inflation psi.
    2016 F350 CrewCab Dually
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    Excessive Payload is a Wonderful Thing

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  8. #8
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    Quote Originally Posted by xrated View Post
    Your tire should NEVER be the weak spot on the truck. A SRW truck with a 7000 lb axle weight rating should have tires that are rated OVER the GAWR of the respective axle. The order of progression on a truck should be as follows.
    1. Add weight until you have reached the available payload of the truck. ( GVWR - actual weight of the truck = available payload.
    2. Once you reach that point, you are at the GVWR of the truck. Any further addition of weight will put you not only over the payload number, but obviously, over the GVWR of the truck.
    3 Next in line, if you keep adding weight to the truck, is the axle weight rating.
    4. After that has happened, if you keep adding weight, you will eventually reach the tire load capacity rating.

    If you exceed all of that, make sure your life insurance is fully paid.......LOL.....seriously though, just don't ever get to the point that you have exceeded the available payload, and you won't have to worry about the other capacities, unless you have never maintained the truck or your tires are not the correct ones, or the correct tires are totally shot and wouldn't have anywhere near their rated load capacity at the sidewall inflation psi.
    HA! Yeah, don't plan on going over payload... but I am thinking with the 351 I am going to be damn close. If it is, I want to make sure all the other components are top-notch.
    ---~-~-~-~-~-~---
    351M & 2018 Ram 3500 SRW

  9. #9
    Long Hauler geotex1's Avatar
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    Quote Originally Posted by NWbulldog View Post
    HA! Yeah, don't plan on going over payload... but I am thinking with the 351 I am going to be damn close. If it is, I want to make sure all the other components are top-notch.
    Likely over. The literature pin weights are notoriously light versus reality for GD. I'm sure owners here would share their experience if you ask directly in the subforum, or just buy the dually and never think about it or the SRW/DRW debate again! �� lol!
    Rob & Nikki + Cloverfield
    2020 Grand Design Solitude S-Class 3350RL
    2015 RAM 3500 Longhorn Laramie Crew Cab, Long Bed, 4x4 Dually Cummins/AISIN

    Mountains of Pennsylvania

  10. #10
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    Quote Originally Posted by geotex1 View Post
    Likely over. The literature pin weights are notoriously light versus reality for GD. I'm sure owners here would share their experience if you ask directly in the subforum, or just buy the dually and never think about it or the SRW/DRW debate again! �� lol!
    Yeah... it'll be close. I have spent to many hours searching for everyone that has posted pin weights for the 351, seen everything from ~2600-3200. It was hilarious watching the GD regional manager the other weekend answer questions about pin weights. Maybe its a clever game I'm playing here... "sure honey, it's going to be close" - Take it to the weight station the day we buy it - "oops... its over, Looks like I need a new truck!"
    ---~-~-~-~-~-~---
    351M & 2018 Ram 3500 SRW

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