# Torque and wheel size of a car

• Automotive
Nick666
So lets assume I have 100 Nm at the wheel of a car, with a wheel size of 25 in diameter

If I put wheels that are 24 in diameter, so 4% smaller, what exactly will change ? Will I have 4% more torque ?

xxChrisxx
Waaat.

You'll have exactly the same amount of torque. Something will change at the contact patch through.

Nick666
Isnt there some formula that might be applied here ? ... F = T*r ? Doesnt a change in wheel size of a car act like a gear change ?

billy_joule
Nick666
Ohhh...its F=T/r ... I get it now.

felmon38
If F is the ground force on the wheel then T- F.r = IG

rsk2mc
Also your rpm changes. The circumference (pi*D) is less on the smaller diameter.

Harshit puri
no you won't have more torque .. torque is a function of gear ratios at wheel torque = engine torque*gear ratios*differential ratio
So when you are considering change in tyre dimensions assume it constant. so for changing wheel selection following things will occur.
in this case your tractive force will increase..