minsicomm

After reading online, I gather you can increase the psi on your tires to gain some mpg?

I have a 07 q7 with the 4.2, and I just put on some new tires about 2k miles ago, and have seen a drop in my mpg. Admittedly, I went from LRR tires to non-LRR tires, but I was expecting a 1-2% drop, not 8-10. The tires are at 35psi right now, recommended by the manual, and I seriously reduced my tire life last time by stupidly keeping them at what the door jamb sticker said (44 front, 49 back).

The tires are great, but they do feel almost too sticky and a bit too soft for my tastes. If I go up to say 37 or 38psi, would I get better mpg and a better ride? Does it affect tire wear in the middle like the 44/49 does? I don't want to wreck my tires, or create an unsafe condition, and I know the Q7 is exactly known for its fuel efficiency, but I was getting something in the neighborhood of 19.5 highway, and 14.5 in the city. Now its closer to 17.5 and 11. Thats a an effect at the pump that I can feel in my wallet. FYI, I'm a conservative driver.

Does anyone run their tires a bit firmer? These are 19" all seasons, not performance or run flats or anything meant for a really sporty ride. I just want to make sure its acceptable to do and not cause damage to anything.

Reggie

I typically run 1-2 lbs over the recommendation for pressures for a unloaded car. I also watch the wear on my tires every six months to see if that works OK. I am a conservative driver too. So bumping them up a lot will help your gas mileage some but at the risk of wearing out the center of your tires early and affecting the handling - I would say a one to two lbs increase will be fine

mishar

Exactly. You proved that by running them at 44/49 and getting better millage. Going up to 40 psi will improve your millage (not as much as 44/49) and won't cause premature wear or hurt ride quality. At least not much.

I just wonder how could tires be too sticky? Unless you are in a drifting competition.

P.S. Ask Q7 people. They have on hand experience.

ECS Tuning-Audi

Bumping the pressure up can increase MPG. The higher pressure is essentially reducing the friction coefficient.

But bumping the pressure up too high can also make a vehicle ride harder as the tire wont give much over bumps and road imperfections.

Jason

minsicomm

I had assumed that the LRR tires were more responsible for the better mileage, which is why I was asking about tire pressure after reading about it. It sounds like it was probably a combination of both.

By too sticky I mean that sure, I appreciate the grip, but it feels like tires want to move just a touch slower than I want them to during the two hard maneuvers I've had to make. Can't explain it. Not quite as marshmallow-like as winter tires in July, but softer than I want. It looks like experimenting with something between 37 and 40 are where I should start,

mishar

Agreed. I would start from 40 for those 2.5 tons.

minsicomm

I experimented the last few days, starting at 40, and I think for me, 38psi feels right. We got a cold snap here (Delaware), morning lows in the 20s, so that had to be taken into consideration, but I think its good. No major difference in turns that I can tell, but it feels firmer to ride on while doing my daily stuff and on the highway. Slight uptick in highway mpg, none in the city so far.

Thanks everyone.