What I did with my new Mission Trailer

[bmwlarry]

The thing about pneumatic tires is that the casing is MEANT to flex sufficiently to let the tread compound heat up & reach it's optimal temperature... it actually needs that flex & the consequent heat build up in order to provide traction as well as to act as another 'shock absorber' component integral to the proper functioning of the suspension, and that flexing also allows the tire tread (& casing) to flex enough to effectively 'wrap' over sharp pebbles, stones, etc on the surface of the road that could otherwise cause punctures.....

Pump your tires (trailer, bike, car, truck, it doesn't matter!!) up to their maximum pressure without the specified maximum loading on them, & you not only won't have tires reaching the appropriate temperature that allows their tread to grip the road surface in the manner designed, you already know you are gonna be wearing out the tiny little strip in the middle of the tread that is the only bit of the tire touching the ground, AND you are also compromising the suspension & it's proper function (might as well run the trailer on the steel rims?!) AS WELL as risking explosive tire failure if you hit anything hard/sharp enough to blow the tire, it doesn't need to be very sharp, just raised & a little pointed. Don't believe that last bit?! Try blowing up a balloon as hard as it'll go without bursting, then just stick your finger or a blunt pencil into it, hard - who's gonna bet that it won't burst?! Cos it will!! It's really easy to burst a balloon (or a tire) that's blown up hard, but blow the same balloon (or maybe another from the same packet, cos the first one you already burst, didn't you!?!) up to half it's maximum pressure & then stick your finger or a blunt pencil into it just as hard as you did earlier to burst the first balloon, & it's very unlikely that you'll burst it!! Simply because the balloon has a fair bit of flex that allows the outside casing to wrap around & absorb the intrusion, just like your tires can if they aren't blown up to their max pressure without the max load on them!!!

As for the bouncing thing & your 'doubts' about loss of control; ANY bouncing that isn't damped by the tires (at an appropriate pressure for the load) & the suspension working together means that the trailer is already spending at least some of the time OUT of CONTROL; & remember, your tow vehicle is securely fastened to that.... however much or how little weight you have back there - PLUS all the momentum that the bouncing around brings with it..... It really doesn't take very much weight or bouncing back there to cause dangerous 'uncontrollable & unrecoverable' loss of control under some conditions, & those conditions are something that you won't necessarily know have been met until it's too late & you've lost more control than you have already just by running your tire pressures high enough to let that trailer bounce in the first place!!

Why run the risk? Why run ALL those risks?? :shocked:

Peter
Thanks for taking the time to educate. All this said, if I am reading the sticker right on this trailer, it says gross Vehicle weight is 1,000 lb and tire pressure is 80 lb. Does this mean if the trailer weight is at its max (1,000 lb) the tire pressure should be 80 lb? If the maximum I ever have is the BPP recommended 400lb - what tire pressure should be in the tires for that load?

Thanks

 

[Peter Aawen]

I believe your tires should have 'Maximum Load/Maximum Pressure' info printed on the sidewall (it's mandatory in Aust) - if it's not there, it should still be available from the tire manufacturer; it's that info, which is worked out & specified by the tire designer/manufacturer, that's used to specify the speed & load rating assigned to the tire, & it's usually something like Maximum Load 1000lbs @ 80psi (that's just an example tho!! Check your tire sidewall or the tire manufacturer's specifications for that tire!) & that Max load/pressure info will be something totally separate to the trailer GVM. This basically means that ONLY if your trailer & its load weighs in at twice the specified max load level (you've got TWO tires under the trailer, don't you?!) should their pressure ever be that high!!

The trailer GVM is worked out & specified by the trailer engineer/designer & might take the tire load limit into account, but the GVM is generally more to do with the strength of the trailer drawbar, the hitch, body, axle, & suspension design etc; once that's all designed & engineered then the manufacturer generally sources a tire that matches or exceeds the load requirement to fit on the trailer.

Here in Aus we have an 'Australian Tyre & Rim Association Standards Manual' where the tire & rim assoc/manufacturers have published info that's done all the work for us for all tires including trailer, LT, & Passenger tire sizes from 30 profile to 80 Profile & specifies the correct pressure required to carry a given load in a tire of the specific tire size/load/speed rating; you should have a similar Tire & Rim Association or Tire Industry Association 'Handbook' published over there. This info is generally gathered from the basis of those load & speed ratings that you see on the sidewalls of your tires; the details published in the handbooks cover all the 'Standards' for things involving tires, rims, valves, wheels, bead profiles, ply ratings, tire repairs, tire pressures, tire/rim fittings, & all that sort of stuff. It might take some wading thru to get the right pressure info, but here in Aust there's a large 'table' at the back of the annually produced manual that specifies the various tire sizes, load, speed ratings, etc & provides load/pressure info. That info &/or your Tire Industry Assoc should be your first port of call for all things about Tires (& rims, etc) :thumbup:

That said, generally a 'rough guide to setting your tire pressures on any vehicle 'right' is to find out how much your vehicle weighs, then divide the max load on each tire by the actual load - using your max trailer weight & my example, that'd mean divide 1000 by 400, the answer's 2.5; so divide the Max pressure by that answer ie 80 divided by 2.5 = 32... but there's a 'rule of thumb' inherent in all things tire related that revolves around 4psi, so cos the tires are rotating, take the answer you get, 32, & add 4 to give you the 'estimated' tire pressure for those tires when carrying 400lbs, ie 36 psi - use that as your cold start tire pressure.

If you want to fine tune your tire pressures further to get them closer to the optimum, you can set that pressure when the tires are cold, & then check to see if the pressure has increased by 4psi after an hours towing. If it has, you're fine; but if it's gone up by MORE than 4psi then your start pressure was too LOW, add air to your tire now & adjust your cold start pressure accordingly; if it's gone up by LESS than 4psi, your cold start pressure was too HIGH, so drop air from your tires now & adjust cold start pressure for next time accordingly. When you need to add/subtract pressure while the tires are hot/warm (ie, after driving for a while) then you add/subtract just 1/2 of the difference between what the pressures actually are & what they should have been if they went up by the 'rule of thumb' mandated 4psi - ie, if they stayed at 36psi when they shoulda been up to 40 psi after an hours towing, the difference between what they are & what they shoulda been is 4lbs, so drop your pressure now by just 1/2 that, ie 2psi & don't forget to adjust your cold start pressure for tomorrow morning too!!

That '4psi Rule' stuff is just a 'rule of thumb' that came from the old & bold tire experts I learnt from many years ago in the racing & road transport game waaaay back, but it's been shown to still work very well today. Some people like to use 6psi instead of 4 when they are working with tires running heavier sidewalls, but AFAIK it doesn't really make a great deal of difference, altho it does tend to make some people more concerned about the lower pressures you get to start cold with, so I don't generally recommend people bother. The 4psi value or it's equivalent is often found built in to the 'over temperature/over pressure' calculations on Tire Pressure Management Systems as well as used widely throughout the tire testing, automotive, & road transport industries, altho it seems to have dropped from the ken of many tire fitting & selling 'experts' these days, dunno why?!? Oh, and do be aware that it is possible to 'over-tire' a vehicle &/or a trailer - if you run a lightweight vehicle or trailer, you really don't need or want to run a massively heavy construction all-steel bias ply load carrying tire - it'll never get up to its optimum temp or work well for what you are doing, so get & fit something more appropriate to the weight/load you are carrying & the vehicle you are running & you'll get better & safer performance from it!

Over to you, to do with (or ignore) as you desire!

 

[bmwlarry]

WOW! thats a lot if info. I will spend some time looking into what my Tire sidewalls say as well as what the trailer says and get back to you. Thanks

I believe your tires should have 'Maximum Load/Maximum Pressure' info printed on the sidewall (it's mandatory in Aust) - if it's not there, it should still be available from the tire manufacturer; it's that info, which is worked out & specified by the tire designer/manufacturer, that's used to specify the speed & load rating assigned to the tire, & it's usually something like Maximum Load 1000lbs @ 80psi (that's just an example tho!! Check your tire sidewall or the tire manufacturer's specifications for that tire!) & that Max load/pressure info will be something totally separate to the trailer GVM. This basically means that ONLY if your trailer & its load weighs in at twice the specified max load level (you've got TWO tires under the trailer, don't you?!) should their pressure ever be that high!!

The trailer GVM is worked out & specified by the trailer engineer/designer & might take the tire load limit into account, but the GVM is generally more to do with the strength of the trailer drawbar, the hitch, body, axle, & suspension design etc; once that's all designed & engineered then the manufacturer generally sources a tire that matches or exceeds the load requirement to fit on the trailer.

Here in Aus we have an 'Australian Tyre & Rim Association Standards Manual' where the tire & rim assoc/manufacturers have published info that's done all the work for us for all tires including trailer, LT, & Passenger tire sizes from 30 profile to 80 Profile & specifies the correct pressure required to carry a given load in a tire of the specific tire size/load/speed rating; you should have a similar Tire & Rim Association or Tire Industry Association 'Handbook' published over there. This info is generally gathered from the basis of those load & speed ratings that you see on the sidewalls of your tires; the details published in the handbooks cover all the 'Standards' for things involving tires, rims, valves, wheels, bead profiles, ply ratings, tire repairs, tire pressures, tire/rim fittings, & all that sort of stuff. It might take some wading thru to get the right pressure info, but here in Aust there's a large 'table' at the back of the annually produced manual that specifies the various tire sizes, load, speed ratings, etc & provides load/pressure info. That info &/or your Tire Industry Assoc should be your first port of call for all things about Tires (& rims, etc) :thumbup:

That said, generally a 'rough guide to setting your tire pressures on any vehicle 'right' is to find out how much your vehicle weighs, then divide the max load on each tire by the actual load - using your max trailer weight & my example, that'd mean divide 1000 by 400, the answer's 2.5; so divide the Max pressure by that answer ie 80 divided by 2.5 = 32... but there's a 'rule of thumb' inherent in all things tire related that revolves around 4psi, so cos the tires are rotating, take the answer you get, 32, & add 4 to give you the 'estimated' tire pressure for those tires when carrying 400lbs, ie 36 psi - use that as your cold start tire pressure.

If you want to fine tune your tire pressures further to get them closer to the optimum, you can set that pressure when the tires are cold, & then check to see if the pressure has increased by 4psi after an hours towing. If it has, you're fine; but if it's gone up by MORE than 4psi then your start pressure was too LOW, add air to your tire now & adjust your cold start pressure accordingly; if it's gone up by LESS than 4psi, your cold start pressure was too HIGH, so drop air from your tires now & adjust cold start pressure for next time accordingly. When you need to add/subtract pressure while the tires are hot/warm (ie, after driving for a while) then you add/subtract just 1/2 of the difference between what the pressures actually are & what they should have been if they went up by the 'rule of thumb' mandated 4psi - ie, if they stayed at 36psi when they shoulda been up to 40 psi after an hours towing, the difference between what they are & what they shoulda been is 4lbs, so drop your pressure now by just 1/2 that, ie 2psi & don't forget to adjust your cold start pressure for tomorrow morning too!!

That '4psi Rule' stuff is just a 'rule of thumb' that came from the old & bold tire experts I learnt from many years ago in the racing & road transport game waaaay back, but it's been shown to still work very well today. Some people like to use 6psi instead of 4 when they are working with tires running heavier sidewalls, but AFAIK it doesn't really make a great deal of difference, altho it does tend to make some people more concerned about the lower pressures you get to start cold with, so I don't generally recommend people bother. The 4psi value or it's equivalent is often found built in to the 'over temperature/over pressure' calculations on Tire Pressure Management Systems as well as used widely throughout the tire testing, automotive, & road transport industries, altho it seems to have dropped from the ken of many tire fitting & selling 'experts' these days, dunno why?!? Oh, and do be aware that it is possible to 'over-tire' a vehicle &/or a trailer - if you run a lightweight vehicle or trailer, you really don't need or want to run a massively heavy construction all-steel bias ply load carrying tire - it'll never get up to its optimum temp or work well for what you are doing, so get & fit something more appropriate to the weight/load you are carrying & the vehicle you are running & you'll get better & safer performance from it!

Over to you, to do with (or ignore) as you desire!