Mechanical Brakes?

Houston Rodder

Houston Rodder

Member
I have properly adjusted mechanical brakes. They stop my vehicle wonderfully. If I switch to 16" wheels with wider biased tires how will that effect my braking. Currently, I am running stock 19" wheels on my 1930 Sedan.
Thanks.
 
Houston Rodder said:
I have properly adjusted mechanical brakes. They stop my vehicle wonderfully. If I switch to 16" wheels with wider biased tires how will that effect my braking. Currently, I am running stock 19" wheels on my 1930 Sedan.
Thanks.
Click to expand...

I had a panic stop the other day that I am pretty sure locked up all 4 of my 16" tires on pavement. It sure sounded like it with the screeching of tires, and based on the faces of the people walking next to me.
 
Doesn't effect the braking at all. I run 600x16s on mine and my crappy hardlined brakes are just as crappy as before.
 
Will increase traction when brakes are applied & also will increase traction when spinning out if drag racing -- if drag racing is ever tried!

Also, less air in tires also amounts to more tire surface on road & increased traction.

Vintage trick when stuck in mud is to let air out of rear spinning tire(s), get out of mud, then pump up tire(s) again.
 
Jordan said:
it will only improve your braking because of the wider grip of the tires.
Click to expand...

This true. Once you reach the point of "slide" then only the sliding coefficient of friction between you and the road determines how far the car will travel. In the case of narrow tires versus wider tires, wider tires wins on the break-away force required and the resultant sliding coefficient of friction.

If in putting on new tires/rims you find a case where you CAN'T slide the tires, it means braking force between the brake shoes and the drums is LESS than the braking force between the tires and road - and some attention to the shoes/drums/system is necessary to achieve braking to the fullest extent possible allowed by your car system.

In truth, sliding friction of the tires is NOT the optimal braking condition. Somewhat less pressure on the brake pedal does this. A condition is desired where the tire rotates slightly at speed less than the travel of the road underneath. This so that new cool rubber is continually presented to the road/tire interface where sliding contact and heat occurs. ABS brakes TRY to duplicate this optimal condition without human interplay or control feedback.

But if you're able to slide the tires, you will probably have a condition where slightly less pedal push will result in a nice optimally short stop.

Gosh, I once drove a 1936 Ford truck that had been retired as a fire truck. Minus the rear body and all the firefighting appointments I could NOT stop that truck without skidding the tires. EVERY TIME it would lock up and would be the devil to control going into a stoplight.

Think about that one.

Joe K
 
Hopefully some auto/mechanical engineer types and tire experts will comment on my post.

I would investigate the use of larger tires further. As an example, I put large/wider tires on my full size modern pick up truck and especially when braking during rain soaked pavement had difficulty keeping the truck on the highway. The footprint of the larger tires resulted in more square inches spread on the footprint on the road surface and therefore less pounds per square inch of traction on wet surfaces. I had to replace the tires with the size initially on the truck because I could not keep it on the highway at more than 35 mph on rain soaded surfaces. Larger tires on the Model A may ride and brake satisfactory on dry surface but might not on wet surface.

Bill Lee/Virginia Peninsula
 
Joe K said:
This true. Once you reach the point of "slide" then only the sliding coefficient of friction between you and the road determines how far the car will travel. In the case of narrow tires versus wider tires, wider tires wins on the break-away force required and the resultant sliding coefficient of friction.

If in putting on new tires/rims you find a case where you CAN'T slide the tires, it means braking force between the brake shoes and the drums is LESS than the braking force between the tires and road - and some attention to the shoes/drums/system is necessary to achieve braking to the fullest extent possible allowed by your car system.

In truth, sliding friction of the tires is NOT the optimal braking condition. Somewhat less pressure on the brake pedal does this. A condition is desired where the tire rotates slightly at speed less than the travel of the road underneath. This so that new cool rubber is continually presented to the road/tire interface where sliding contact and heat occurs. ABS brakes TRY to duplicate this optimal condition without human interplay or control feedback.

But if you're able to slide the tires, you will probably have a condition where slightly less pedal push will result in a nice optimally short stop.

Gosh, I once drove a 1936 Ford truck that had been retired as a fire truck. Minus the rear body and all the firefighting appointments I could NOT stop that truck without skidding the tires. EVERY TIME it would lock up and would be the devil to control going into a stoplight.

Think about that one.

Joe K
Click to expand...
Holy tire smoke! Thanks.
 
Houston,
The tread on my new bias ply Coker Classic 6:00 X 16's is only a tiny bit wider than the Firestone 19" tires on the car I sold.
Bill W.
 
I'm with Bill I have 4, 33 16 inch wheels/tires that I am putting on, stacked up beside 4, 31 19 inch wheels/tires that I took off , and the two stacks are within a half inch of each other.
 
You will stop faster with less skidding. (:

If your mechanical brakes are good it shouldn't matter what rim is on the car.
 
jkeesey said:
Q, im pretty sure a 33 had 17" wheels. I believe 35 was the first year for 16".
Click to expand...

My bad, you are right. I did look at the stack of 33's. I have a stack of 35's too, and will take a look when I get back home.

But I really don't think there is enough difference in tread width that the driver would see any appreciable stopping distance change, although theoretically there would be some.
 
He did originally state 16"s with a wider tire, not necessarily stock so they would help in a skid situation with more rubber to the road.
 
jkeesey said:
Q, im pretty sure a 33 had 17" wheels. I believe 35 was the first year for 16".
Click to expand...

My bad, you are right. I did look at the stack of 33's. I have a stack of 35's too, and will take a look when I get back home.

But I really don't think there is enough difference in tread width that the driver would see any appreciable stopping distance change, although theoretically there would be some.
 
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