My XKR says fronts 33 PSI and back 36 PSI. I went to my dealership today because the tires just LOOKED flatter in the front. They said it was about 32 in each so they pumped it up to 34 PSI. Immediately the car feels MUCH IMPROVED. Should there be more PSI in some brand tires regardless of the request in the door for 33/36? Is that on the TIRE? Where can I get this info. I have 255/285 Conti DWS 06's

Loth

 

Standard tires for the XKR are the Dunlop Sportmaxx's. A summer tire. the DWS 06's are a all season tire.

Loth

 

The tires and air pressures provided by the car manufacture are usually optimized for the best overall comfort , performance and wear. There should be no difference between tire makes so the air pressures on the door are for all tires of the same size regardless if summer or all season or winter tires. Now if you track the car then that is a different animal and usually tire pressures are experimented with to get optimum performance. Consider what happens if you inflate the tires over the mfg. recommendations. More pressure will result in maybe easier steering as you will be riding more on the center of the tire tread. This will also produce faster wear in the center. Lower pressure is the opposite effect. You can play with pressures and if you find a pressure that make you feel good for your driving then go with them.

 

I made the mistake of purchasing the DWS-06 tires for my '10 XKR. Placing the factory pressure settings on the tire they felt like they had mush for sidewalls. Handling dropped way off when compared to the old standard Dunlop tires. Ride, however, was improved.

I was super disappointed due to the soft sidewalls and loss of precision from the handling. I raised the tire pressures to 40 psi all around which returned some of the precision, at the expense of the ride.

Just a couple of days ago I reset the tire pressures to try 36 psi all around and the sense of softness in the handling returned.

Rather disappointed with the DWS-06 tires. Guess, it works for people who place ride comfort ahead of handling. For me they do not work well at any tire pressure.

 

Tire pressures can be distinctly different between brands and purpose. The door placard is a general approximation, used only by the average driver that cares little about getting the most from them or the car.
There are several ways to get tires properly inflated, the most accurate is with a temperature probe or Pyrometer. A person with track experience can read inside, center, and outside temps and tell you if you are over inflated, under-inflated or even if your camber is off. Tread temps can be used very accurately, and you can even find tire pressures may vary from side to side depending on the cars center of gravity.
Another common trick is to monitor how far over on the sidewalls your tires roll in hard cornering. A majority of tires have a roll-over indicator (for lack of a better term) which marks the end of the primary tread, and the beginning of the sidewall. (Note the small arrow)




If you are under inflated, and rolling too far on the sidewalls, you loose stability. Over inflated, you loose grip.
Quickest way to test this is to use chalk or white shoe polish and mark the sides (about the size of the red circle). Go for a hard drive, and check where the white has been scrubbed off, and inflate/deflate accordingly. You don't want to be on the sidewall at all, but using as much of the tread as possible. Adjust pressure to scrub to the red line shown, and see how the car feels.

As for axr6s experience with the DWS, (I've not driven the newer -06 series) they are well respected tires, and certainly not a set that should be on a California car unless you live solely in the mountains. The DWs would have been a far better choice.

Tire pressure is indeed important, and can vary by compounds, vehicle center of gravity and your desire to get either average performance or maximum performance out of them.

If your an in-town lollygagger, then stick to the placard as a good middle of the road setting, otherwise I encourage all to read up and study tires and how to get the most out of them.

Vince

 

^^^^ What he said ^^^^

 

You make a good case for the majority of us owners. I suspect most enjoy the car for cruising or long weekends or running around town and not for performance type driving. The OEM Dunlops that came on my 12 and only had 6K miles on them were hard , noisy and slick on wet roads. These are all of the features I didn't want so I looked for the compromise. Ended up with the DWS 06 and it completely met my need. So my needs are opposite of yours and it's up to others to make a decision. Good summary .