Tyre pressure

cahooney · 14 July 2012, 09:48

Does anyone know what my tyre pressure should be on my boat trailer ? I'm towing a 4m searider with a 45hp Mariner 2stroke outboard.

thomas · 14 July 2012, 10:34

I started at 30psi, if it bounces about too much let some air out, If it looks too flat put a bit more in, I don't think there are any set pressures like you get with cars, you just experiment to find what's best for you'd set up.

Dhf · 14 July 2012, 10:35

I would say 25lb should do, you don't want them to hard because that'll make your trailer to bouncy.
ps, I would love to hear you doing a radio check with the Coast guard, there gonna love your call sign,

actions · 14 July 2012, 12:46

Quote:

Originally Posted by Dragonhawk ficht

ps, I would love to hear you doing a radio check with the Coast guard, there gonna love your call sign,

Brilliant, Just Brilliant.

Bigmuz7 · 14 July 2012, 16:13

Just watch though .. there will be a maximum pressure on the side of the tyre

bear in mind it will increase when the tyre naturally heats up with use

Trailer Guy · 14 July 2012, 17:06

Standard tyre pressures here: Trailer & Towing info

But I reckon you'll be running 4.00 x 8, 5.00 x 10, 5.20 x 10 or 145R10 on a small RIB?

If so, here's some tyre pressures for smaller wheels and tyres (as Bigmuz7 states, the cold max tyre pressure will be on the side of the tyre wall):

4.00 x 8" 4 ply = 60psi
4.00 x 8" 6 ply = 75psi
4.00 x 8" 8 ply = 86psi

5.00 x 10" 6 ply = 50psi
5.00 x 10" 8 ply = 65psi

5.20 x 10" 4ply = 32psi

145 R10 std = 42psi
145 R10 8 ply = 65psi

Whilst it's tempting to drop some pressure out, to eliminate bouncing, don't do too much - under inflated tyres will wear quicker, heat up due to additional friction (ergo may heat bearings and disperse grease) and will effect your fuel economy. Hope that helps.

PS. +1 on the name

cahooney · 14 July 2012, 17:18

Much obliged for the replies folks

ps do you think I should change my call sign

kerny · 14 July 2012, 17:21

Is it best then Trailer Guy to just inflate the tyres to the psi stated on the tyre and leave it at that, being as the maximum pressure stated is cold.

Mercury · 14 July 2012, 17:39

Quote:

Originally Posted by cahooney

Much obliged for the replies folks

ps do you think I should change my call sign

Yea "Kiss Ass"

cahooney · 14 July 2012, 17:45

Now thats got to take some licking

Trailer Guy · 14 July 2012, 19:06

Quote:

Originally Posted by kerny

Is it best then Trailer Guy to just inflate the tyres to the psi stated on the tyre and leave it at that, being as the maximum pressure stated is cold.

Hi Kerny, it's what I do on every trailer service, providing the tyres are cold.

kerny · 14 July 2012, 19:08

Quote:

Originally Posted by Trailer Guy

Hi Kerny, it's what I do on every trailer service, providing the tyres are cold.

Thanks TG I will stick to that then

Bigmuz7 · 14 July 2012, 20:17

Quote:

Originally Posted by kerny

Thanks TG I will stick to that then

It depends what you are doing ... sometimes if you need to launch over a pebbly/rocky shore for example, having really hard tyres makes your boat jump about whilst you manouvre over them.

Personally I never inflate to maximum, full pressure is more likely to pick up punctures from debris IMO due to less ability to flex, and also removes some inherent suspension ability of the tyre its self. It also impairs road holding, and your trailer will behave differently with regards to drift etc. The sidewalls play quite an important part in this regard, and do the job less effectively if they are really stiff.

Everyone will have their own view ofcourse, having trailed many different types of trailers both at work and play, with a wide variety of loads, Ive concluded it just seems to work best this way

kerny · 14 July 2012, 20:22

Quote:

Originally Posted by Bigmuz7

It depends what you are doing ... sometimes if you need to launch over a pebbly/rocky shore for example, having really hard tyres makes your boat jump about whilst you manouvre over them.

Personally I never inflate to maximum, full pressure is more likely to pick up punctures from debris IMO due to less ability to flex, and also removes some inherent suspension ability of the tyre its self. It also impairs road holding, and your trailer will behave differently with regards to drift etc. The sidewalls play quite an important part in this regard, and do the job less effectively if they are really stiff.

Everyone will have their own view ofcourse, having trailed many different types of trailers both at work and play, with a wide variety of loads, Ive concluded it just seems to work best this way

muz7 my tyres say max 44psi so would it be a safe bet then to run at 40psi for road use ?

mick · 14 July 2012, 20:27

I am with muz on this one mine are 65 psi max but I run mine around 60 psi

willk · 14 July 2012, 20:30

I've always run mine a shade under max, on the basis that I wasn't running them under the full load they were designed to carry.

kerny · 14 July 2012, 20:37

Mines an unbraked trailer and the maximum limit is 750kg so when the rib is loaded with fuel, anchor and equipment I'm up to the limit.

Bigmuz7 · 14 July 2012, 20:45

Quote:

Originally Posted by kerny

muz7 my tyres say max 44psi so would it be a safe bet then to run at 40psi for road use ?

Well .. My 5.4 Tornado sits on a single axle trailer, but its quite a light boat,because its only a single console etc etc and I cant rember the tyre size coz its at work.. but from memory .. thats the max pressure on mine aswell, I checked them recently because one looked a bit softer than I would like, on checking it was at 30 so I put it to 35 and it looks fine at that, and more importantly .. equalled the other one.

Its all relative to the load its carrying, the tyre will have it stamped on it as to what its maximum load is.

If you need to use the trailer in particularly arduous terrain, you can also fit it with higher load index tyres, with heavier lay up, but again road performance varies accordingly.

I'd normally expect to see some sidewall deformity under normal conditions and load.

With a lot of modern cars using low profile stuff, we are very used to seeing no deformity at all these days on a tyre, but trailer tyres have a much larger sidewall and need to be assessed differently

Trailer Guy · 15 July 2012, 15:30

Agree with all of the above - it's all relative and down to your personal discretion and preference.

Trouble is, when you're doing paid work, for someone else (who often isn't there, on site), you need to make a decision over the requirement and the last thing I want is someone ringing me to tell me I haven't inflated their tyres enough etc. I guess what I'm saying is I've got to do them all the same and if I inflate them to the tyre pressure stated on the wall / in my notes, then it's up to the customer if they want to run them at a deifferent pressure.

As everyone says - have a tow and make an educated decision, on the result, at the end of it.

kerny · 15 July 2012, 15:49

Thanks for all your advice TG, and yes I think common sense is the major factor here, like willk says, if you are up to the trailer weight limit then Maximum air pressure.