Originally Posted by Klubbheads

marketing bullsh!t. Any year coupe or sedan including G37s will not blow their engine on 87 octane. They will be slow as **** but nothing will happen.

Originally Posted by RPL

^LOL Klubbs, I just noticed that I made your sig! Sweeeeet I wish I had a c/f drive shaft

hahha

Originally Posted by Blue Dream

^^ You suck. I was hoping for a good race video.

SBF!!!

Originally Posted by DaveB

I'm not quite sure where you're getting your information regarding tire weight, but a quick check of tire weights on TireRack shows that, on average, 215/55R17 tires are generally 2 to 4 lbs lighter (24-26lbs) than a 245/40/19 (27-30lbs). The OEM 17s weigh in the 24-25lb range and the coupe 19s are very close to that (within a pound). I'm not surprised your aftermarket 19s are lighter (probably close to 20lbs), but the tires make up the loss when compared to the 17" OEM setup.

Then there's two other major factors at play:

1) With larger rims, the mass of wheel/tire is further from the hub which makes it harder to accelerate.

2) Wider rims/tires and sticky tires greatly increase drag and wind resistance. A 245/40/19 is over 1.5" wider in profile. That's a big increase in drag.

My aftermarket 18" combo weighs 1lb less overall than my OEM 17s. The width of the 18" combo is 1.2" wider than the 17s. Overall, when I swap rims, my MPGs drop a solid 1-2mpg. That means the car is using my fuel/power to overcome the drag.