Is it normal for my S2000 to drive like it has square tires for the fist mile on cold mornings? Tire pressure is normal, non-abused with 2300 miles. Has anyone else discovered a better performing engine when the tank is at 3/8 or below (please don't tell me "less weight")?

 

could be, especially if they are cold. so what are the tire pressures? not warmed up but cold in the morning.

 

I noticed this a few days ago after leaving the car parked several days. I think the tires are "flat spotting", or "taking a set" when left in the same position for an extended period of time. I used to use Yokohama A032R's on another car and it felt like a Flintstones car for the first few blocks. It seems that softer tire compounds are more susceptible to this.

It's nothing to worry about, they should spring back to shape after driving a few minutes.

 

I'm glad somebody else posted about this and referenced Yokohama tires as well. I felt something like a slight flat tire (or tires) a couple times about a week ago but all the tires were properly inflated. I worried it might be something else (maybe the diff?!?). I felt it only during the first few miles after the car sat for a while and it was most noticeable at speeds over 40mph. I haven't noticed this during warmer weather like today and yesterday (~75F in Phoenix -- this is why I live here). I have Yokohama tires and now I suspect they are a little temperamental when they don't get much attention.