Got Dueler D697LT - what pressure do you run?

[jammers]

Just swapped over from pirelli scorpion ATR (two for sale in the markets :)) to the Bridgestone D697LT 265/60R18. Never had LT tyres before so wondering what pressures people run?

I ran the pirellis at ~38psi around town which seemed fine.

[Tombie]

I found they work well at the Placard recommended pressures....

Except offroad... Then down they go :)

[Redback]

I have 36psi in the front but kept the placard pressure of 38psi for the rear, works well for me.

Baz.

[go-disco4]

Just swapped over from pirelli scorpion ATR (two for sale in the markets :)) to the Bridgestone D697LT 265/60R18. Never had LT tyres before so wondering what pressures people run?

I ran the pirellis at ~38psi around town which seemed fine.
When absolutely fully loaded to GVM I ran 38 and 44 (cold) on highways

works well

Only a little bit bouncy when empty, but I have left it there for the roads

ran around 26 - 28 (cold) in the Vic high country

around 20 (cold) in the Simpson, and adjust when it got hot, even a bit lower with very soft sand

seems to work

GD-4

[SimmAus]

I run at 40 around town (which was tyre installer suggestion).

Recent Vic High Country - run at 30-33 and no problems.

Cheers

[jimc]

dunno if its the right advice or not, but I was told many years ago to significantly up the pressure when on highway as the manufacturer specs a lower pressure so the tyre can provide some cushioning.

I run d697's and to test I recently ran 52psi on a trip to Flinders Ranges and fuel economy seemed better for it! The ride was little harsher, but the weight of the camper seemed to iron out most of that.

I even did skytreck with those pressures, but I reckon I could get a stock commodore around those tracks.

[Tombie]

The std is the bigger the rubber the lower the pressure.

Running at 52psi is going to result in:

Centre tread wear exceeding outer edge wear.
Reduced road grip in wet conditions.
Decreased ride comfort
Increased chance of puncture
Tread block damage offroad

[jon3950]

dunno if its the right advice or not, but I was told many years ago to significantly up the pressure when on highway as the manufacturer specs a lower pressure so the tyre can provide some cushioning.

I run d697's and to test I recently ran 52psi on a trip to Flinders Ranges and fuel economy seemed better for it! The ride was little harsher, but the weight of the camper seemed to iron out most of that.

I even did skytreck with those pressures, but I reckon I could get a stock commodore around those tracks.

Manufacturers will specify a pressure that gives what they consider the best compromise between ride and handling. In simple terms, increasing tyre pressures on bitumen will improve handling, while reducing pressure will improve the ride. On dirt, reducing pressure will improve handling while still improving the ride. For normal on-road driving, both on bitumen and dirt, this shouldn't be more than a couple of psi either way in my experience.

To take this a little further, tyres have an optimum pressure at which the grip level is highest. Reducing or increasing the pressure from this point will reduce the level of grip. This will vary according to road conditions and load - eg, it will be higher on bitumen than on dirt. Running at this pressure is what you aim for when racing or rallying as grip is everything, however manufacturers tend to specify pressures a little lower than this as they are also trying to provide a decent ride.

Increasing the pressures significantly (ie over the optimum) will improve fuel economy, as it reduces the rolling resistance of the tyres by reducing the amount they flex. This comes at the cost of not only a harsher ride, but more significantly less grip and greater suspension wear as higher loads are transmitted through the suspension components.

The tyres form an important part of the suspension system. The flex in the sidewall absorbs the low amplitude vibrations from the imperfections in the road surface, leaving the springs to absorb the high amplitude vibrations such as bumps and potholes. This reduces the amount of vibration transmitted through the suspension components to the body, reducing levels of NVH and also reducing wear in suspension bushes. It also allows the tread of the tyre to remain in contact with the road surface. This reduction in grip level can become dangerous, particularly in the wet.

Increasing the load on a tyre (ie vehicle weight) will require an increase in pressure. This is needed to maintain the amount of sidewall flex at an acceptable level. As you load a Disco the load on the rear tyres increases more significantly than the load on the front, because most of the weight will be added near to or behind the rear wheels, moving the cog towards the rear. Note the placard on the D4 recommends increasing pressures in the rear more than the front as you load it for this reason.

Given all the above, I would suggest that 52psi in any tyre on a D3/4 is overinflated. This is particularly so on the front, where you will be experiencing considerably reduced levels of grip.

Cheers,
Jon

[discojools]

The std is the bigger the rubber the lower the pressure.

Running at 52psi is going to result in:

Centre tread wear exceeding outer edge wear.
Reduced road grip in wet conditions.
Decreased ride comfort
Increased chance of puncture
Tread block damage offroad

And much less grip...therefore more dangerous...especially in the wet. I have had 2 very scary occasions when unknown to me service people had upped the pressure to mid 40s!
I run mostly + 2psi on manufactures recommended due to extra weight of bull bar and long range tank.

Jon below puts it all in a nutshell

[Graeme]

Increasing the load on a tyre (ie vehicle weight) will require an increase in pressure. This is needed to maintain the amount of sidewall flex at an acceptable level.I suggest its the contact patch area that has to be maintained, achieved by flexing the sidewall appropriately, although with more weight the contact patch needs to be bigger to get the same grip.

[jon3950]

I suggest its the contact patch area that has to be maintained, achieved by flexing the sidewall appropriately, although with more weight the contact patch needs to be bigger to get the same grip.

Kindasorta.

The larger the contact area, the greater the amount of grip. However for any given contact area, the higher the load the greater the amount of grip; and for any given pressure, the higher the load the larger the contact patch. This is why wings are used on racing cars.

The contact patch though is essentially determined by the amount of flexing in the sidewall.

Its probably worth noting here that grip consists of two components - lateral, or cornering, and longitudinal, or acceleration and braking. A tyres total grip is constant so the harder you are braking or accelerating the less grip is available for cornering.

The flexing of the sidewall will also affect the slip angle - that is the angle between the direction of rotation of the tyre and the direction of travel. Lateral grip will increase with slip angle up to a point, beyond which it then decreases. Increased sidewall flexing will mean this higher slip angle will be reached at a lower cornering force - ie lower speed or larger radius. This essentially means the tyre will reach its limit of adhesion at a lower speed.

Hope this makes sense, I may need to edit it in the morning.

Cheers,
Jon

[Redback]

Agree 100% with jon3950, coming from a racing background myself(albeit motorcycles) the principle is the same.

Well said Jon.

Takes me about a week of driving testing with different pressures to get the best setup that suits me, anal I know.

For towing I have 38 front, 44 rear.

Baz.

[PaulGOz]

Fully loaded with 200kg plus on the tow ball and steel bull bar I run 38 psi front and 50psi in the rears. I have been experimenting bringing this down in the rear and will probably start running between 46 and 48 psi in the rear. Having set those pressures this is really only suitable for high speed freeway. I do this for economy and once on secondary bitumen still at high speed I will take the rears to 44 to 46psi and the front to 36psi cold, this improves the ride the car gets a bit to fidgety at the higher pressures on secondary roads. I go down to 24 psi front and 30 psi rear on dirt and low speed. I also have tpms so am still experimenting with effect on temps.

Some othrr factors to consider are that this tyre has a max pressure of 65psi in the265/65×17 so we are still a way off that but on the rear axle we would be getting closer than most vehicles using thisvtyre to the max load.

[Redback]

I have to add that this is all a compromise, because road conditions change with temps and surfaces, so getting a good setup one day, can change the next day, but who changes there pressures to suit each day or even a rainy day:cool:

Baz.

[jimc]

Following on from yesterdays comments.

Since returning from trip, pressure has been returned to 42 - 44psi. I have aux tank and RWC that adds extra rear end weight.

While on the trip, I had significant additional weight on and in the car; family of 5 with associated "stuff", water, fridge, drawer etc etc etc...plus trailer made sure of that!

The tyre was driven at reasonable speed over varied terrain and I could not fault the tyres..even at the higher pressures. Goes to show they are bullet proof!

[captcam68]

Hi all,

Had two sets of the 694's on my D3 and have new set of 697's on 18" compo motives.
I run 38 front and 40 rear cold on the road bumping the rear to 42 cold when the car is loaded. 2wd / good cond. dirt roads drop to 30 and 32 and when it starts getting anywhere near low range stuff 24 and 26. Sand when I do it which isn't often start at 16 all round and work down if reqd.

Always had great road holding on tar both light and loaded, wet and dry and never had a puncture whilst offroading ( 2 on road from nails from building site two doors down!)

Have 3 sets staun deflaters labeled for different surfaces ( too lazy to change them).

The above pressures work well for me with tweaking reqd. when faced with hours of lovely corrugations ahead of you. Regardless, the duellers have been an awesome tyre and wouldn't contemplate another brand, great value at approx $350-$370 tyre. Super quiet on road and got 60K out of previous sets only swapped them cos I wasn't happy with depth of tread left for offroad. Happy to do this as I don't run 2 sets of rims/ tyres and most of my miles are long distance black top.
Stick with what your most happiest with!

[jammers]

Thanks all for the advise. A recent trip to zig zag tracks I ran 25 all around lightly loaded. The tyres were great I was really happy. Can wait to find some tracks again soon.