Wow, this was such a beautiful explaination. My god. I want to go back to physics so I can follow along with that. So yes, the old tire does have about 3500 miles on it. My stock Pirellis had lasted until 18,000 miles, at which point I had gotten these new PS4S. Honestly, I had gotten my energy out in the first 20k miles and had been driving it like a Honda Accord nowadays. I'm not planning on driving it hard/ launching it anyways.I think your control arm is fine. The problem is the new tire (left tire). No matter how small the difference in the treads, it is best to replace both rear tires together. If one tire has more tread than the other, the car will pull to the one with more rubbers.
In physics, I can think of two explanations:
1) Generally car moves when torque of the driveshaft < torque of the friction (Td < Tf). On the other hand if Td > Tf, the car slips. Torque of friction (Tf) is calculated with this formula Tf = (WD or weight distribution of car to each tires) x road friction x (TW or tire width / distance from axel to end of tire).
So you see, when a tire has less tread, it has less TW. This means it has smaller torque friction or smaller Tf.
Comparing your new left tire and old right tire:
Left tire: has larger torque friction or larger Tf.
Right tire: has smaller torque friction or smaller Tf.
2) Also, there is a difference in kinetic friction between new tire and old tires. This kinetic friction happens when the tires are rolling and will affect acceleration.
a = F of the friction / mass
acceleration = 0.5 x m x g x kinetic friction / mass of the car
So during hard acceleration, your car will pull to the left.
Haha glad you like the explanationWow, this was such a beautiful explaination. My god. I want to go back to physics so I can follow along with that. So yes, the old tire does have about 3500 miles on it. My stock Pirellis had lasted until 18,000 miles, at which point I had gotten these new PS4S. Honestly, I had gotten my energy out in the first 20k miles and had been driving it like a Honda Accord nowadays. I'm not planning on driving it hard/ launching it anyways.
Your explanation makes sense.
So what we have here is a case of torque steering right? I had just gotten concerned because I had read that torque steering could be caused by a suspension issue (Although my mechanical knoweldge is zilch to none, this is all just google searching).
I do also remember the pressure in the right rear being 2.5barr, while everywhere else it was 2.7barr. I'll go and get this adjusted, but could that play into it?
Another note, the harder I accelerate, the harder it pulls left. And again, when I drive this car like a honda accord, I can't even tell anything is wrong. So in that case, it's even less likely a suspension/ alligment issue right? Because otherwise I would get the pull in other cirsumstances too, like braking, gentle acceleration, and cruising.
My dad had a Gallardo he recently traded in for LP610-4...his 560-4 pulled hard to one side... took it to the dealer (where I work) for an alignment, they never did the alignment because he had larger after market forged rims and cup 2's...they kept giving us the run around saying they rack says it already drives straight... long story short bigger rims could have been the issue (which I know is hard to believe), are you running factory spec? also tread life may for some reason be off on one side, I'd recommend getting an alignment and making sure they have the same amount of tread on both sides for starters...So here's what happened. I got a flat tire on my rear driver's side. The tires were PS4S. I called a flat bed and at the time I didn't realize, but in order to pull the huracan onto the flat-bed, the tow truck driver attached the tow strap onto what I believe is the driver's side suspension control arm. He did not use the tow-hook on the front bumper. I just got the car back today from the dealer with only the damaged tire replaced with an identical PS4S. (I opted not to change the other rear tire). The passenger rear tire is unchanged, and I'd guess I have used up 4/32 to 8/32s of the tread. I drove the car home today and noticed that ONLY during modest to hard acceleration, the car pulls to the left. It's not an extreme pull, but it's very much there. It does not pull at all if I drive normally, accelerate normally, brake, etc. This left side is the same side as the new tire, and also the side where the car was pulled up by the tow strap. So let me hear it guys, did the tow truck driver damage my suspension control arm? When I visually examine the control arm, it appears to be okay. Could this be the result of un-even tread on the rear tires? Could the car just be out of alignment? Keep in mind everything was fine before the flat incident.
It helps after many years of riding a sleigh with deer powersakura, i though you are just a santa with a violin
Thank you my friend for the complimentsInteresting question and great explanation by @Sakura who is not only our resident chemist but now, apparently, our resident physicist. My friend in addition to your Santa hat you have many others hats as well. BTW, agree I always change the tires in pairs as well.......now I know why based upon the physics.
I think tire makers would also love this explanation to sell more tiresSakura, you have made me a believer! Love that detailed explanation. I would also love to see the OP explain that to the dealer!