Got Dueler D697LT - what pressure do you run?

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Originally Posted by Graeme

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.

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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

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.

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.

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.

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!

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!

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.