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  1. #1
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    Default Trailer tyre advice

    I recently bought a trailer, but the problem is that it is too high for my vehicles tow ball, so it sits leaning down when towing. It has quite large tyres, 75 profile. So my question is, if I reduce the profile to say 60, will I get the full reduction at the nose, or is there anything that I am missing. Note that these tyres are not standard, the previous owner fitted them because he did a lot of off-roading.
    Is there anything else that I could do to reduce the height?
    I would prefer to make the adjustments on the trailer rather than the vehicle, so things like drop plates etc are out of the question.

  2. #2
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    Default Re: Trailer tyre advice

    Change tyres but should always be slightly nose down.
    There is no task too simple for some people to complicate !



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  4. #3
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    Default Re: Trailer tyre advice

    I guess it depends on how nose down it is, but like duncang said, nose down is good, nose up is a problem. Perhaps you can provide more details on the trailer/tow vehicle? I agree with changing the trailer instead of the vehicle though.


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  6. #4
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    Default Re: Trailer tyre advice

    You could look at a spring over vs spring under conversion, but that would assume that there is space between the leaf springs and the chassis? Assuming it has leaf springs. You could look at mounting the tow coupling higher? Ie mount it on some square tubing etc that would get things back into a even keel? I am assuming a relatively light trailer. If it is heavy then any such changes need to be thought through properly and engineered appropriately.

    Smaller rims and tyres? Air Springs. So many options.

    Do you have any photos of the rig attached to tow vehicle? This would assist in better understanding how much you need to lower the trailer and how big the trailer is?

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  8. #5
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    Default Re: Trailer tyre advice

    Before changing to many things, go to a tyre size calculator website (just google tyre size calculator) and check how much lower the 60 profile tyre will be compered to the 75 profile. Half of that will be your axle drop and maybe its all you need.

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  10. #6
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    Default Re: Trailer tyre advice

    You supplied a bit too little info regarding the exact problem, such as measurements etc.
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  12. #7
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    Default Re: Trailer tyre advice

    What was the standard tyre size. A picture might also help. What tow vehicle are you using. Maybe a drop plate will solve the problem.

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  14. #8
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    Default Re: Trailer tyre advice

    Quote Originally Posted by Erwin Schimper View Post
    What was the standard tyre size. A picture might also help. What tow vehicle are you using. Maybe a drop plate will solve the problem.
    OP said drop plates are out of the question.
    Current - 2009 Mazda BT50 3.0CRDi 4x4 d/c
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  16. #9
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    Default Re: Trailer tyre advice

    He said no drop plate type solution (Not sure why since that may be the simplest solution.
    Yes - that means that he needs to change something on the trailer.
    More info. needed to help with any sensible tips.
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    Default Re: Trailer tyre advice

    Quote Originally Posted by Peter1949 View Post
    He said no drop plate type solution (Not sure why since that may be the simplest solution.
    Yes - that means that he needs to change something on the trailer.
    More info. needed to help with any sensible tips.
    Drop plate will increase the problem, his trailer hook is too high!
    Last edited by 340; 2021/09/02 at 03:05 PM.

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    Default Re: Trailer tyre advice

    Quote Originally Posted by 340 View Post
    Drop plate will increase the problem, his trailer hook is too high!
    I used a drop plate on a Ford Laser. I raised the gooseneck. I guess the item is called "drop plate" but one can use it for a "raise plate" or "lift plate" also.
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  20. #12
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    Default Re: Trailer tyre advice

    Maybe it should be call adjustmant plate. It can be used to lower of raise plate. It works up or down posistion. I have seen with 4 hole and 6 holes.

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    Default Re: Trailer tyre advice

    If you go with changing tyre ratios remember to get rated tyres. Insurance wants it like that
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    Default Re: Trailer tyre advice

    Quote Originally Posted by Sam vd Merwe View Post
    If you go with changing tyre ratios remember to get rated tyres. Insurance wants it like that
    Please excuse my ignorance, but what is this rating for - c rated for commercial? And why is it required?
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    Default Re: Trailer tyre advice

    Quote Originally Posted by stephenplumb View Post
    You could look at mounting the tow coupling higher? Ie mount it on some square tubing etc that would get things back into a even keel?
    You need to mount the coupler lower to make the nose higher - which is usually a tad more difficult than raising the coupler on a pedestal.

    The 60 and 75 are aspect ratios of the width of the tyre. So if this is a 245, the height changes from 75% of 245 to 60% of 245. That's 36 mm. If the tyre is narrower like a 205, then the difference is 30mm.

    Look at raising the axle, the points to consider here are how much travel you have under trailer. If you have lots, maybe the leafspring mounts can be shortened, leafsprings can be flattened, or as mentioned, just fit the axle above the leafsprings.

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    Default Re: Trailer tyre advice

    Quote Originally Posted by Groenman View Post
    Please excuse my ignorance, but what is this rating for - c rated for commercial? And why is it required?
    Yes. Its commercial. Loadrating is much higher and blowouts is less. Make sure by your insurance first. My friend had a claim rejected because of that
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  25. #17
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    Default Re: Trailer tyre advice

    Thanks for all the replies thus far. It's clear that without pictures, the solutions will be difficult to arrive at. So please see attached. It might not look very tilted, but while I am driving, i can see the entire roof of the trailer.<br>Size of the tyre is 30x9.50R15
    Attached Images Attached Images  

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    Default Re: Trailer tyre advice

    I would leave it as is - looks fine to me.

    My previous vehicle had the trailer towing basically level. Since changing the vehicle my trailer tows nose down (Like yours) and it is seems way more stable on the road.

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  28. #19
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    Default Re: Trailer tyre advice

    Quote Originally Posted by Peter1949 View Post
    He said no drop plate type solution (Not sure why since that may be the simplest solution.
    Yes - that means that he needs to change something on the trailer.
    More info. needed to help with any sensible tips.
    Reason being that from what i've heard and read is that the towball height is determined in accordance with the position of the chassis, so moving it up or down changes the direction of the forces placed thereon. I know that much cleverer people than myself have done the calculations and in their opinion (which may be right) it will be fine, but I would prefer to tweak the cheaper of the 2.

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    Default Re: Trailer tyre advice

    I also think that looks fine, but if it bothers you changing the tires would probably be the easiest way to go.

    The internet tells me 30/9.5R15 is roughly equivalent to 235-75R15, so it would depend on how much lower the trailer needs to sit, I can't really comment on that based on the photo. Perhaps you can measure the distance from the A-frame to the ground once hitched, then unhitch and adjust the A-frame height using the jockey wheel until it looks right to you (remember some downward angle is needed), then remeasure and find the difference. Once you have the result (eg. 20mm) you can look for a tire that will have a diameter reduction of double that (40mm).

    Here are some examples:

    235-75R15 --> 28.8" --> 0 reduction = 0
    225-70R15 --> 27.4" --> 1.4" reduction = 17.5mm
    205-65R15 --> 25.5" --> 3.3" reduction = 41.2mm
    205-60R15 --> 24.7" --> 4.1" reduction = 46.1mm

    etc.

    Use a tire size calculator to get to the size you need, I would recommend you don't reduce the profile too much as trailer tires usually have as high a profile as possible. It would be a good idea to find out if your local tire shop would be willing to fit the tire and then see if the trailer sits right behind your car before committing to buying.

    I use this tire size calculator, but there ae many good ones out there:

    https://www.1010tires.com/Tools/Tire...ismetric=False


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