Forum Discussion

cruz-in's avatar
cruz-in
Explorer
Mar 07, 2014

Tire Clearence Question

Hi All,

Going to replace my 5th wheel tires with LT (not looking to enter the ST versus LT debate with this thread). As the sizes are different, looking at clearence issues. I currently have 235/80 R16s

1 do not want to increase height (as there are wires running over tire) so 235/85s are out. this leaves my options as:

245/75 or 225/75.

I am kinda partial to the 245/75s as we freguently drive/park/camp on grass/dirt/etc. and spreading the load over a wider tire seems to make sense to limit (somewhat) sinking in.

245/75s are slightly wider than the current 235/80s (about 0.4 inches). So my question. What is reasonable left/right clearence for a tire? Current 235/80s have a little over an inch between the sidewall the grease fitting on the wetbolts.

My figuring is that 245/75 could reduce this to about 0.8 inches.

Thanks
Dan
  • edatlanta's avatar
    edatlanta
    Explorer
    Mar 07, 2014
    Look at the outside diameter of your existing ST235/80-R16E and compare to the LT235/85R16 potential replacement.

    The GY Marathon ST235 has an outside diameter of 30.7" and their G614 LT235/85R16 has the exact same outside diameter of 30.7". Therefore there will be absolutely no clearance change. But if you don't need the G rated tire or want to keep the cost down, the G614 might not be an option for you.
  • cruz-in's avatar
    cruz-in
    Explorer
    Mar 07, 2014
    Humm....using the available tire calculators (online), they show

    235/80 with a diameter of 30.8
    and
    235/85 with a diameter of 31.7
  • Miles_Away's avatar
    Miles_Away
    Explorer
    Mar 07, 2014
    I don't think height will be an issue, however you must consider the clearance between the front and rear tires.
  • Me_Again's avatar
    Me_Again
    Explorer III
    Mar 07, 2014
    OP is talking about width not height. He already said he is not going with the 235's because of wiring above the tires. His question is about the slightly wider 245's.

    Given the size and weight of OP's trailer and 4400 pound axles, I think the LT215/85R16 rated to 2680 is the best choice, as it is similar in diameter to his current tires. Bridgestone Duravis R250 steel ply carcass will last 6-8 years for him.

    Chris
  • iawoody2's avatar
    iawoody2
    Explorer
    Mar 07, 2014
    The difference of .9 on diameter is only .45 from axle to top of tire. If his wires are that close I would be very concerned with the existing tires.
  • Me_Again's avatar
    Me_Again
    Explorer III
    Mar 07, 2014
    iawoody2 wrote:
    The difference of .9 on diameter is only .45 from axle to top of tire. If his wires are that close I would be very concerned with the existing tires.


    From OP original post.

    "1 do not want to increase height (as there are wires running over tire) so 235/85s are out. this leaves my options as:

    245/75 or 225/75."

    He also wrote.

    "I am kinda partial to the 245/75s as we freguently drive/park/camp on grass/dirt/etc. and spreading the load over a wider tire seems to make sense to limit (somewhat) sinking in."

    At his weight, I believe he is over thinking this part. Wider is not necessarily the best thing for a trailer tire.

    Both the 215/85R16 and 225/75R16 are a better match to his trailer weight than the 235/85R16 and 245/75R16. With the larger tires rated to 3042 he will need to run lower inflation, to prevent center of tread wear issues and beating up the trailer, which defeats the reason to install them.

    Chris
  • iawoody2's avatar
    iawoody2
    Explorer
    Mar 07, 2014
    What I was saying is that if .45 is too tall he should be concerned about wiring with existing tires, especially as the trailer bounces down the road.
  • aruba5er's avatar
    aruba5er
    Explorer
    Mar 07, 2014
    aside from diameter, what is the load carrying capacity of each versus what you have now. I don't have a chart handy but the ST has a higher load carrying capacity than a simalar LT. Like others said you only raise it by half inch approx.
  • Me_Again's avatar
    Me_Again
    Explorer III
    Mar 07, 2014
    aruba5er wrote:
    I don't have a chart handy but the ST has a higher load carrying capacity than a simalar LT. Like others said you only raise it by half inch approx.


    The higher load carrying capacity is due to speed restriction on 65MPH and lower testing standards. OP said he did not want to get into that discussion! He most like already is aware of the short comings of ST tires.

    His trailer has a GVWR of just over 10K and 4400 axles. LT tires rated to 2680 will serve him well and will out last ST tires by two or three times.

    Chris

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