Increased air in tires to sidewall max -> +10% mpg

[Subyman]

Funny. I have a green 1995 F150 5MT V6 with about 150,000 miles. It's a little beat up on the outside, but it's mechancally sound, the engine doesn't even burn a drop of oil. I also have a 2000 Insight 5MT with 180,000 miles, which I'd trust to let my grandmother drive across the country.

I suspect I enjoy my vehicles a lot more than many on here do, and with my current savings rate, I won't be commuting for 30 years as I'll be able to retire in my early 30's.

Money is power and freedom. Possessions are baggage and liability.

Ouch! I didn't mean to hit you square between the eyes with my hypothetical.

 

[monkeydelmagico]

Ask your self, why hasn't braking distance significantly improved over the last 30 years on cars? Tires certainly have gotten wider, brakes have gotten better, tire compounds have gotten better, yet to get less than 100ft of braking distance from 60mph is nearly unattainable.

When I ask myself the answer seems to be yes, braking distances have improved. This despite many vehicles getting bigger/heavier until very recently.

Sub 100ft braking isn't all that great when the car behind you ends up parked in your glove box.

 

[tortillasoup]

When I ask myself the answer seems to be yes, braking distances have improved. This despite many vehicles getting bigger/heavier until very recently.

Sub 100ft braking isn't all that great when the car behind you ends up parked in your glove box.

Weight doesn't really have that large of an impact on braking distances if the brakes and tires are up to snuff. If you put brakes that are appropriately sized for a 5000lb vehicle onto a 2000lb vehicle, the 2000lb vehicle, assuming everything else is equal isn't going to brake any faster.

 

[cabri]

Weight doesn't really have that large of an impact on braking distances if the brakes and tires are up to snuff. If you put brakes that are appropriately sized for a 5000lb vehicle onto a 2000lb vehicle, the 2000lb vehicle, assuming everything else is equal isn't going to brake any faster.

Try taking a sub-compact at 60mph and hitting the brakes.

Then do it with a full size car or 1/2 ton truck.

Stopping distance is much longer..

There is more momentum behind a 5000lb object than a 2000lb object.
The stopping surface (brakes/tires) is not 2.5 x as much

 

[monkeydelmagico]

Weight doesn't really have that large of an impact on braking distances if the brakes and tires are up to snuff. If you put brakes that are appropriately sized for a 5000lb vehicle onto a 2000lb vehicle, the 2000lb vehicle, assuming everything else is equal isn't going to brake any faster.

But if you put the brakes from a 2000lb vehicle on a 5000lb vehicle, assuming everything else is equal, isn't going to brake any slower. Especially if you overinflate the tires on the 2000lb vehicle before you put it's brakes on the 5000lb vehicle. Then it just totally up to weight snuff-ing and the angle of the road crown.

 

[tortillasoup]

But if you put the brakes from a 2000lb vehicle on a 5000lb vehicle, assuming everything else is equal, isn't going to brake any slower. Especially if you overinflate the tires on the 2000lb vehicle before you put it's brakes on the 5000lb vehicle. Then it just totally up to weight snuff-ing and the angle of the road crown.

I don't even know where you're going with what the hell you're saying. If you put brakes from a 1 ton onto a 2.5ton vehicle, it's probably going to have longer braking distance. Remember, if the car's ABS is kicking in or the car is skidding, better brake pads and or rotors isn't going to have any effect on braking distance. That was my point about putting brakes from a truck on a car, cars today are pretty good at skidding/engaging ABS anyway with the brakes they're equipped with.

Try taking a sub-compact at 60mph and hitting the brakes.

Then do it with a full size car or 1/2 ton truck.

Stopping distance is much longer..

There is more momentum behind a 5000lb object than a 2000lb object.
The stopping surface (brakes/tires) is not 2.5 x as much

Braking distance in a Tesla Model S is very good and it's a 5000lb vehicle.

While there is more momentum on a 5000lb vehicle compared with a 2000lb vehicle, there is more grip on the 5000lb vehicle due to the weight. So, if the brakes on the 1 ton vehicle and the 2.5 ton vehicle are both capable of wheel lockup, then braking distance should be similar assuming all other aspects of vehicle design are similar such as suspension geometry, tire compound, etc.


The reason the above is true is because once a vehicle is capable of locking up its brakes/engages ABS, the only way to improve braking distance is to change suspension design and or tread compound.