Math Question: Gear ratios. 1991 Q45

[youngq45r]

Does any one out there know the equation for figuring out the gear ratio for if you put on bigger or smaller tires? I have slightly smaller tires on the Q, and it i drove another q the other day and it didnt sem to accel as fast as mine. How Much does the tire sise affect the overall speed/acceleration/ gas milage of the car? And finaly, I know it sounds stupid, and would look VERY stupid, But has anyone every put on a really small tire, like a 14 or 16 inch , for running at the track? My dad says it would increase 1/4 mile times dramaticaly, would it? Thanks for all the help on NICO!

[maxnix]

Gear ratios are different in the first two gears for ealy and later G50.

Start with the value for the constant Pi.

[bullittandy]

That's a good question. I know that top fuel dragsters use the expansion of their rear tires to increase their top speed (numerically "lower" rear gear). I don't know how much they expand though, seems like its almost a foot.

Anybody else?

[Q45tech]

Where most miss the boat is not realizing that tires placed on a car become unround and the loaded radius is the important dimension.

Published loaded radius is a guess about a generic average car.

Depending on inflation and inherent sidewall stiffness and the weight on the tire 1/2>3/4" reduction in radius is the norm on rear tires.

26:................ 26/2= 13 - 0.5 = 12.5 x2= 25.0 x pi =

Each tire would need to be tested for loaded radius at a range of psi and the internal psi vs internal air temperature calculated [usual rule is 1 psi per 10F].

Dealing with foot pounds a 24" loaded diameter would be transparent to diff ratio, whereas a 25" would change the effective gearing by 4.166%

[elwesso]

overall tire size is going to have to differ a lot to give any difference on paper.

The Q you drove probably had bad knock sensors and other things.

[youngq45r]

Thanks. But would happen if you would put a 16 or smaller on? How much would it help?

[bullittandy]

Where most miss the boat is not realizing that tires placed on a car become unround and the loaded radius is the important dimension.

Published loaded radius is a guess about a generic average car.

Depending on inflation and inherent sidewall stiffness and the weight on the tire 1/2>3/4" reduction in radius is the norm on rear tires.

26:................ 26/2= 13 - 0.5 = 12.5 x2= 25.0 x pi =

Each tire would need to be tested for loaded radius at a range of psi and the internal psi vs internal air temperature calculated [usual rule is 1 psi per 10F].

Dealing with foot pounds a 24" loaded diameter would be transparent to diff ratio, whereas a 25" would change the effective gearing by 4.166%

Tech,

I'm going to forward you an article on the importance of conceptual analysis in the scientific method. Specifically, clarifying the meaning of concepts and communicating them in a grammatically and comprehensible way.

[elwesso]

I understood what he was talking about.. The OP asked for math, tech gave him math, problem solved.

[Haitian_King]

I'm better with word problems.

Lol.

[bullittandy]

I understood what he was talking about.. The OP asked for math, tech gave him math, problem solved.

says the engineering major!

[Q45tech]

Just like we all learned in previous lessons, a 4% increase/decrease in rear [tire tread to road surface] torque does not change the acceleration much.

Quarter Mile time = 6.9446 X (weight / HP)^0.2841

http://autopedia.com/stuttgart....html

[maxnix]

Tech,

I'm going to forward you an article on the importance of conceptual analysis in the scientific method. Specifically, clarifying the meaning of concepts and communicating them in a grammatically and comprehensible way.

You obviously are not a scholar of Q45tech's posts. While abbreviated, all the information is there for those capable of minimal analysis.

[Haitian_King]

To a layman, that explanation sir, is quite the conundrum.