Going from 15s to 18s hurt my acceleration.

[Zedzag]

I took a spin with my new wheel/tire combo on friday. I played around with a buddy's car to see what the added traction was worth. With the old 15s we were door to door...now he pulls me pretty good. I guess the added weight of 10lbs per wheel, increased diameter and distance of mass relative to the axis of the 18s explain why my car feels sluggish. I also had a passenger but I attribute most of the "power loss" due the the extra power needed to turn those big wheels.
Can anyone confirm this with any dyno or track stories of big and heavy vs small and light dia wheels?

I'm still glad to have gone bigger, I just need more power now lol.

[69Bbird]

You also change your gearing with bigger tires. Is there a diffrence in the over all diameter? You might need to lower you gear ratio to get your acceleration back.

[Zedzag]

Overall tire diameter is the same but it feels as if I changed the gears to a higher(numerically lower) gear.

[Boesch]

Adding 10 lbs per wheel is quite a bit. Is that a "wheel and tire" weight or just the wheel weight increase?

[Zedzag]

That's wheel and tire weight so 40lbs total.

[Boesch]

I'm not horribly surprised that your performance was hurt quite a bit. A total of 10lbs increase on the wheel and tire combo, when you were at 30lbs, is a 30% increase. That's a pretty large increase. I've seen similar things when people put 22's on new suburbans and such. All that extra rotating mass takes longer to get spun up and it also takes a lot longer to stop as well.

[parsonsj]

Can anyone confirm this with any dyno or track stories of big and heavy vs small and light dia wheels?This subject has been covered many times here. You'll also find your braking performance compromised for the same reasons. Bigger diameter rims hurt acceleration, in both directions. It's just physics. Moment of inertia, and all that.

jp

[Dwbiggs]

I wouldn't think 40 lb would make that much difference...what do they say, 100lb will add 1/10 sec to a 1/4 mile run?

[Boesch]

I wouldn't think 40 lb would make that much difference...what do they say, 100lb will add 1/10 sec to a 1/4 mile run?

That's in added weight to the car, not to rotational unsprung mass.

[Zedzag]

It's the added rotational unsprung mass that I feel not total added weight to the vehicle. Yes braking is also affected. I've read some old posts and lot's of good discussions confirm these facts. I'll just have to add more power to compansate :6gears:

[nekkidhillbilly]

why im gonna run 16s nice medium between both