Topic: Tire pressure and extra loads?

[quadzilla]

When adding a load to your car, be it extra people, luggage, junk.how much should you adjust (increase) your tire pressure by?

For example, when traveling with only 1 or two people (including the driver) I’m sure the base pressure is fine.

But what about 4 people, some camping gear, roof box with more gear, and even a couple of bikes?

Is this something that I need to worry about?

[tpl]

Some/most cars have this information on the sticker inside the drivers door.
Regular load and full load pressures for instance for each size of tire specified by the mfr. Used to be that there would be  regular driving and sustained high speeds but I guess the lawyers stopped that one.

[quadzilla]

Some/most cars have this information on the sticker inside the drivers door.
Regular load and full load pressures for instance for each size of tire specified by the mfr. Used to be that there would be  regular driving and sustained high speeds but I guess the lawyers stopped that one.

I may need that one also 

So I guess I do the math for everything in between? 

Lets say base = 32 lbs and max = 42 pounds.  If I load the car up with half of max capacity then I would add 5 pounds to each tire.  Is it that simple?

[HeliDriver]

Hmm, I don't ever recall seeing a vehicle with different recommended pressures for "full" or "regular" loads.

I thought that the recommended pressure given on the door jamb sticker was sufficient for all loads right up to the GVWR (i.e. max. for the vehicle).

Of course, if you plan on exceeding the vehicle's GVWR (not that hard to do once you start adding roof boxes, bike racks, etc.), then I suppose you might want to add a bit of extra air pressure in the tires. Of course, exceeding the GVWR isn't exactly a wise thing to do in the first place...

[dr_spock]

Hmm, I don't ever recall seeing a vehicle with different recommended pressures for "full" or "regular" loads.

I thought that the recommended pressure given on the door jamb sticker was sufficient for all loads right up to the GVWR (i.e. max. for the vehicle).

Of course, if you plan on exceeding the vehicle's GVWR (not that hard to do once you start adding roof boxes, bike racks, etc.), then I suppose you might want to add a bit of extra air pressure in the tires. Of course, exceeding the GVWR isn't exactly a wise thing to do in the first place...

It is not on a Honda sticker but VW stickers have different pressures depending on load and speed.

[tpl]

Some/most cars have this information on the sticker inside the drivers door.
Regular load and full load pressures for instance for each size of tire specified by the mfr. Used to be that there would be  regular driving and sustained high speeds but I guess the lawyers stopped that one.

I may need that one also 

So I guess I do the math for everything in between? 

Lets say base = 32 lbs and max = 42 pounds.  If I load the car up with half of max capacity then I would add 5 pounds to each tire.  Is it that simple?

No!  Base would probably be given for the car with a regular person in each  front seat. Max would be for ( in your case) 5 people plus the trunk fully loaded.  I bet that if you look in the owners manual it will give the max load for the car and that will be about 1000 lbs or so +/-.

So the difference is maybe just 500lbs on 3500lbs or so. 

[morty]

Some vehicles do offer different pressures for loaded. There are actually tables published by the TIA, but they are not readily available to the public. How much load are you looking at? What tire did the vehicle come with (size and load index)? What are you running now (size and load index)?

[quadzilla]

The car is a 2005 Mazda 6 Wagon with the OE tires (Michelin MMX4? in 17's)

I checked the door jam and it said 32 lbs and 850 lbs capacity.

Some vehicles do offer different pressures for loaded. There are actually tables published by the TIA, but they are not readily available to the public. How much load are you looking at? What tire did the vehicle come with (size and load index)? What are you running now (size and load index)?

Was thinking of 4 people in the car.  2 bikes on the back using a trailer hitch, 2 in the trunk and a 15cf roof box for the camping gear. 

The more I think about it, I'm pretty close to max capacity.  Maybe I should just rent a mini van?  Can you get four road bikes, four bags and a large cooler in the back of those?

[Snowman]

This weekend I bump up the tire pressure for my ATV dump wagon from 5 to 8 pounds because I was hauling crusher dust which has a high specific gravity and low swell factor.  I do the same for my cars or truck.

[tortoise]

You run Rut Ro II's tires at 8PSI?

[Snowman]

You run Rut Ro II's tires at 8PSI?

See two posts up^

[tortoise]

Hehehehe, that doesn't erase the meaning of:

"I do the same for my cars or truck."

There's no ass like a literal ass.

[Trainman]

You run Rut Ro II's tires at 8PSI?

See two posts up^

Your edit did not change the meaning of what you wrote.  But whatever turns your crank.........      

This weekend I bump up the tire pressure for my ATV dump wagon from 5 to 8 pounds because I was hauling crusher dust which has a high specific gravity and low swell factor.  I do the same for my cars or truck.

[Snowman]

  This means I bump up the air pressure.  Any dummy knows there is not 5 psi in a car or truck, why state the obvious?

[tortoise]

Meh, don't worry about it..
Things sometimes get taken a little too literal around here and I was playin' along.

[Snowman]

 

[je]

What is this for? To keep the tire from being destroyed, for ride, or safety???

[capriracer]

"........What is this for? To keep the tire from being destroyed, for ride, or safety???........"

Safety!!!!

When tires are operated they generate heat.  The more load on a tire - or the less the inflation pressure - the more heat that is generated.

Heat is the tire killer!!!

So in the summer months, it is much more likely for a tire to fail than in the winter.  The same is true for speed - the faster you go, the more heat is generated - but this is complicated by the centrifugal forces being generated at the higher speeds.

So many vehicle manufacturers will give to 2 pressures - one for a single driver, and one for fully loaded.  (I guess they figure you are smart enough to figure out what it would be in between)

But there are some vehicle manufacturers who take the absolutely "safe" route and specify the inflation pressure based on the worst case.

[mar1990]

But there are some vehicle manufacturers who take the absolutely "safe" route and specify the inflation pressure based on the worst case.

 

Maybe that's why most of the tires on my vehicles always seem to wear in the middle rather than the edges. I keep them at the recommended pressure.

[tpl]

Wearing only in the middle is usually a sign of overinflation. 
You are using the recommended pressure from the sticker on the drivers door jamb or the owners manual ?