[QUOTE]Originally posted by Swede_S2k

 

[QUOTE]Originally posted by FCGuy
Warning: here comes a physics digression...

For a disk, I=0.5*m*r^2.

 

I agree 1 to 1.5 is the lower limit, thus underestimated. As I mentioned, max is 1 to 2 (all the weight at the exact outside of the wheel+tire, which is obviously not the case). No way it can be 1 to 4. So, it is between 1.5 and 2.0.

Tire weights can be higher than wheel weights. On my Miata, the wheel is 15.5 lbs, the tire 20 lbs. Is that what you assumed?

Back to the S2000, the '04 OD is virtually the same as the '03 due to the lower profile. So, not a big inertia change there.

 

I agree. The tyre is heavier than the wheel, the tyre is now 1 inch thinner, so mass has moved outward. It's further compounded by the fact that mass distribution is not favourable when comparing a 17in wheel with a 16in wheel.

:ctually it wouldn't be too difficult to compute an exact number given a profile of mass distribution. It would still not reflect other handling issues like road to tyre contact, that may justify a more pessimistic rule of thumb.

 

[QUOTE]Originally posted by Road Rage
I saw it, and I agree anything is possible - but those are two different topics.

 

Yes Stan, I'm well aware of the sprung vs unsprung weight issues. My point was the weight. For every lb of the 25 that can be attributed to the bracing it means one less is attributed to the new wheels/tires and their rotational mass. As you so aptly pointed out, the fewer made up by the wheels the better.

ron

 

Does anyone know when VTEC kicks in on the new motor? I used to think that my (02) VTEC range was too brief, but if you compare it either in rpms or %of the rev range it is rather long in comparison to other systems including other VTECs.

 

>>>But I do not agree with the rule of thumb. It's actually a pretty simple calculation. If the wheel weight is evenly distributed, a fair assumption, then each lb of wheel weight adds an additional half pound of inertia over the normal one lb. Unless I'm missing something??<<<

In many ways, wheel/tires act like multiple, large, slow rotating flywheels in term of their effect on acceleration.

Real world, when you catully measure it, most of the "damage" to acceleration seems to occur in the lower gears when you use heavier wheel/tire combos. (that's a long sentence)

Stan