Originally Posted By: sicko
Originally Posted By: OVERKILL
Dude, how the heck can a tire make your car slower? Were they 50lbs heavier each? Were they a different diameter reducing the mechanical advantage of your differential?
LRR tires can effect a small change in fuel economy but they certainly aren't advertised as a power booster, LOL!!
I don't know, but it was immediately noticeable the moment I drove the car after having them put on. It takes more gas to get get the vehicle up to speed, and the car slows down faster after I take my foot off the gas. I put the tires on in early October, so I've put about 6k-8k miles on them, and it's still the same. I also rotated them a week or two back, and it's been the same. I have been meaning to take the car in for an alignment since it pulls slightly to the right, but I don't think that'll have an impact on the gas/power issue.
The tires are the same size as the originals, both are listed as LRR, and surprisingly the Michelins are listed as 2 pounds lighter on Tirerack.com.
Obviously the tread on the original tires had worn down over the years. However, they still had enough tread left on them to safely go another year or more if needed. I just never liked how they handled in snow/ice, which is why I decided to switch them out a year early before the winter started.
I don't know what's causing it, but the only thing that changed was the tires, and it was immediately noticeable the first time I drove the vehicle after having them installed. I was still in the parking lot where I got the tires installed, and I was already noting/commenting on the difference.
I don't doubt that you felt the car was slower. Nor does OVERK1LL, I'm sure.
The question is why, and the answer can't be the tires. It's physically impossible for a set of tires to make a car that much slower unless the new set is massively heavier and has a ton more rolling resistance. You said you went from a LRR tire to a 2 lb lighter LRR tire of the same type, so there's literally nothing left about the tire that would make the car slower.
There are all kinds of other possible explanations. Maybe the mechanics who installed your tires did something to cause the ECU to change the fuel trims/timing as they pulled it in and out of the shop. Maybe you were just paying extra close attention to the car after you got the new tires installed and perceived it to be slower, and once you blamed the tires the idea stuck with you. This is why people in industry and science do actual testing with numbers before they draw conclusions.
Either way, whatever explains the feeling you got, it can't be that the tires are actually slowing your car down.
