Tyre Pressure

[Ben JK]

Hey getting mixed messages what to run out Maxii 265/75 on our 2009 Nav D22

Thoughts pls?

Cheers
BK

 

[MANNING]

Got this from a patrol forum

I think as every car is different, weights, accessories, terrain
Youd be best making your own number

4 PSI RULE

 

[Bruce Brodie]

Mate I've had 3 D40s, 2 X 2.5 litre fours and 1 V9X V6 turbo diesel, I've always run them at 40 PSI all round and running BFGoodrich All terrain TAs and Micheline I average 140,000 before I need new tyres, always rotate every 10,000 klm front to back and back to front, keep an eye on balance and wheel alignment as well.

 

[tweak'e]

depends on the tires and the load you run.
some of the maxi's are around 60-80 psi.
the max pressure on the sidewall will give you an idea of the pressure per load.

 

[user 52833]

Hey getting mixed messages what to run out Maxii 265/75 on our 2009 Nav D22

Thoughts pls?

Cheers
BK

Listen to Bruce Brodie.

 

[ben85]

40's about right.
140k that's awesome for a set of tyres.

 

[Bruce Brodie]

40's about right.
140k that's awesome for a set of tyres.

Depends on how you drive as well as amount of load but I've dow that 3 times, tyre size is only slightly wider and higher than normal, best part is the Speedo is only 3 ks out to the GPS.

 

[Rhino1174]

I personally like mine at 40psi on my d40 it’s good all round performance can add bit more if you load up bed otherwise get good ride and mileage I find the 38 the tyre fitters put in them a little soft and sidewall flex too much in corners maxxis rzr 265/65/17

 

[Horatius]

I ran mine according to tyre placard (around 33 psi from memory). Far more comfortable (think the engineers overlooked the need for suspension in the D22 lol). That's unloaded though. When fully loaded it's 42psi all round until I reach the dirt. Then it depends on conditions.

 

[Bruce Brodie]

The tyre placard is there so that you get a more comfortable ride, go to any defensive driving course and they will explain it in detail why you should always go higher than the manufacturers placard.

 

[tweak'e]

the tyre placard is only relevant if you have the factory tires.
with 4wd tires there is a lot of variation of the pressure they need for the load.

 

[Horatius]

The tyre placard is there so that you get a more comfortable ride, go to any defensive driving course and they will explain it in detail why you should always go higher than the manufacturers placard.

Defensive driver training course? lol

It sounds like these "defensive driver trainers" might benefit from a "basic physics" course.

It's not like the Nissan engineers (who do understand physics) went to great lengths to come up with these numbers or anything (I checked...it's 32 front, 35 rear or 38 with maximum load for a D22 with standard 265-70's). They obviously just winged it at what seemed comfortable and left it for people on the internet to sort out, they always know better lol.

With the caveat that asking what tyre pressure to run is like asking "how long is a piece of string" (as it's dependant on so many variables) and the op has very slightly larger tyres anyway, but all things being equal, the tyre placard is a good reference point.

Try this little experiment......

Pump your tyres to 40+ psi (in fact go as high as you like) and try them in a variety of conditions (in the wet and dry, on the hwy and dirt roads) and see how you go.

Then try the same tyres at recommended (placard) pressures.

Which one do you find grips the road better, and stops better? Which one aquaplanes earlier? Which one loses it on corrugations earlier (especially cornering)? I would be surprised if it would require experiment, most will have the experience to already know the answer to this.

 

[Bruce Brodie]

Talk to any decent mechanic and he will back up what I stated, the tyres perform and last longer at 40 PSI in a D40.

 

[Horatius]

the tyre placard is only relevant if you have the factory tires.
with 4wd tires there is a lot of variation of the pressure they need for the load.

True that.

Though what 90% of of people run around on are basically highway tyres anyway, marketed as "AT's". Also what many people consider a "full load" often equates to "way overloaded". So probably the only correct answer is to "suck it and see".

That muddies are generally way stronger tyres and can take higher pressures doesn't mean de facto they require higher pressures (if anything I find the opposite). For the same size tyre the placard is still a good reference IMO.

There are people running around on way over inflated tyres in general (particularly utes/4wd's) so that the tyres, last longer or for fuel economy, or because someone told them to. Not necessarily the best idea IMO.

 

[Horatius]

Talk to any decent mechanic and he will back up what I stated, the tyres perform and last longer at 40 PSI in a D40.

They'll last longer for sure, have heard of numbskulls going to 60 psi for this reason (probably better fuel economy as well). If 40 psi is what Nissan engineers settled on, then that will probably be the all round best compromise (but I highly doubt they did settle on that and you might have overlooked that we are in the D22 section).

The trade off with over inflating tyres is that they will not be as comfortable, and the performance will suffer, compared to the very same tyre at lower (placard) pressures. I find it surprising that anyone believes otherwise, but hey, go for it.

Will probably have an effect on longevity of suspension parts too, but that's debatable and, anyway. If you find higher pressures the go, it's up to you. I just find it strange that people feel the tyre placard should simply be ignored to begin with. It's a good place to start.

The more of your tyre that is in contact with the road, the better that same tyre will grip the road. Seems simple, but apparently not. This has to do with friction and some principles regarding motion that Newton worked out for us about 400 yrs ago.

Up to a certain point of course, beyond which the sidewall could suffer and the tyre risks rolling off the rim around corners (which is generally why higher pressures are used at load). But I find it unlikely that a team of engineers and millions of dollars of r and d are going to overlook all of this in their figures.

I have also talked to "decent mechanics" who say the exact opposite of yours lol. Then again, have also talked to "decent mechanics" who believe in ancient aliens, so I don't find such vague anecdotes very convincing. lol

 

[Bruce Brodie]

Car manufacturers like to sell cars, a comfortable ride is more pleasing than a more firm ride, we did a test on a Commodore sedan at eastern creek inflated to 28 psi they put it through a tight corner at 60 kph, it almost rolled off the rim, did the same at 38 psi and it went around the same corner at the same speed more controlled. It's up to you, do what you want, I can only tell you what I have found from 53 years of driving, the last 20 years averaging 40,000 klm per annum.

 

[Horatius]

Car manufacturers like to sell cars, a comfortable ride is more pleasing than a more firm ride, we did a test on a Commodore sedan at eastern creek inflated to 28 psi they put it through a tight corner at 60 kph, it almost rolled off the rim, did the same at 38 psi and it went around the same corner at the same speed more controlled. It's up to you, do what you want, I can only tell you what I have found from 53 years of driving, the last 20 years averaging 40,000 klm per annum.

That's an anecdote at best though. Compared to the r and d that goes into the handling design of passenger cars it's not convincing. For the normal conditions that people drive in, placard pressures on standard tyres won't have them coming off the rim (is "almost" coming off the rim like being "almost" pregnant?). While it will give you better grip than over inflated tyres, you'll almost certainly lose traction on either before that happens (probably better if it does, with the other likely option a roll over).

When they do roll off, it's usually from a slow leak over time leaving it under inflated, or from being overloaded.

Or driving like a maniac. At that stage though, the tyre is only one of the things that can give way (before you exit the roadway) and a few psi here or there doesn't matter. What it reliably indicates in that instance, is that you shouldn't have a drivers licence.

"You can believe me because I have lots of stories" isn't convincing.

 

[Rhino1174]

Now fellas just to throw a spanner in the works you also need to consider if the tyre is rated as an LT also as these need slightly more pressure than standard road tyres so the placard is only giving you info for standard tyre casing and so if you really want to be specific on the pressure speak to the tyre manufacturer with the weight of the vehicle and they will give you the absolute optimum number otherwise your tyre fitter should have a reasonable idea and personal preference of ride has to be taken into account always. I said my preference earlier in the post and my reasons I don’t see why it’s such a big problem for some people to accept