HELP! AWD/Tire wear/Transmission issues? [Archive] - Audi Forums

: HELP! AWD/Tire wear/Transmission issues?


chash1982
07-18-2012, 08:44 AM
So I purchased my car approximately 10,000 miles ago, and I suspect it was about 3/4 of the way through its second set of tires. (Pirelli P6 All Season). After driving it particularly fast for about 25 minutes last week, I started to notice that the front driver's side tire wall has started to show more noticable wear. Sure enough, the tread is also more worn on that tire. Did the penny test and my tires are DEFINITELY done. anyway, here is my question....

I've heard that with Quattro, if the tires are worn unevenly it may cause transmission issues with the vehicle. I hadn't really thought of it at the time, but there were TWO random occasions where I felt a sudden shudder when shifting from second to third in the past couple of weeks. Currently, I am not driving it very far or fast until I can put new tires on it, but my question is this.

1. Could this be early signs of a transmission problem? My car doesn't do anything else unusual, like get stuck in gear, or over-rev.

2.When I replace the tires, do I really need to replace all 4 at once? The back ones need replaced too, but the front ones are the ones that I'm worried about. If I can get away with replacing just the front tires for a few weeks, is it safe to drive the vehicle?

mullardel34
07-18-2012, 01:35 PM
Worn tires really don't stress the transmission on an Audi Quattro vehicle; the "binding" forces are exerted on the Quattro system differentials. There's a really good description of the Quattro system on Wikipedia (Quattro (four-wheel-drive system) - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Quattro_%28four_wheel_drive_system%29)).

All other manufacturer's AWD (all-wheel drive) systems are "reactive" in nature; they all wait for wheel-slip to be measured at one of the four wheels, then those "reactive" systems must actively respond to re-aportion the drive forces between the four wheels. In effect, the "reactive" AWD drive systems are "behind the curve", responding to drivetrain events "after the fact".

With an "active" AWD drive system like the Audi Quattro, the drive forces are inherently distributed to all four wheels in a balanced fashion at all times, even when you're employing engine-braking for deceleration (don't try one that in a BMW or Mercedes or Subaru in snowy/icy conditions...). One of the keys to the Audi Quattro system is the Torsen-based center differential (Torsen - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Torsen)). Of course, Audi Quattro-based vehicles do accrue some power loss in the driveline, due to the "always connected" AWD Quattro system, but the increased fuel consumption is more than compensated for by the increased dynamic stability of the vehicle and the amazingly sure-footed all-weather capabilities inherent to Audi Quattro-based cars. :D

With an Audi Quattro, if the tires are more worn on one end of the car, the uneven rotational speeds of the wheels (due to the unmatched tire circumferences) can induce some binding forces within the driveline and that could lead to some premature wear of the multiple Quattro drive-line differentials. It's usually best to keep the tire-wear balanced front-to-rear; just do proper position-to-position tire rotations every 5K-to-10K-miles on the odometer.

Good luck! :cool: