Anyone consider using run flats to save weight?

[eviljoeker]

Most luxury cars these days use run flats to avoid putting a spare tire out back, anyone consider this when shopping for new tires?

 

[POS VETT]

Whoa whoa whoa, back up a bit.

In case you didn't know, a run-flat tire weighs substantially more than a regular tire. The weight of a spare tire assembly is, at least, a static and sprung weight. Four run-flat tires will introduce a very substantial increase in rotational moment of inertia and unsprung weight. A big no-no in performance and ride quality. The massive Brembo calipers and large rotors coupled with steel suspension arms and cast iron spindles/hub carriers are nightmare enough as far as unsprung weight goes. There is no need to add extra unsprung weight and extra rotational moment of inertia.

 

[eviljoeker]

Whoa whoa whoa, back up a bit.

In case you didn't know, a run-flat tire weighs substantially more than a regular tire. The weight of a spare tire assembly is, at least, a static and sprung weight. Four run-flat tires will introduce a very substantial increase in rotational moment of inertia and unsprung weight. A big no-no in performance and ride quality. The massive Brembo calipers and large rotors coupled with steel suspension arms and cast iron spindles/hub carriers are nightmare enough as far as unsprung weight goes. There is no need to add extra unsprung weight and extra rotational moment of inertia.

I wasn't aware that run-flats weigh substantially more.

 

[jatleson]

I think having a spare is a huge bonus. My current car comes from the factory with run flats. The difference in ride quality between a regular tire and run flat is night and day. When I go on road trips I roll the dice that I don't get a flat, because I run regular tires and no spare.

Sent from my SM-N950U using Tapatalk

 

[winningGT]

Whoa whoa whoa, back up a bit.

In case you didn't know, a run-flat tire weighs substantially more than a regular tire. The weight of a spare tire assembly is, at least, a static and sprung weight. Four run-flat tires will introduce a very substantial increase in rotational moment of inertia and unsprung weight. A big no-no in performance and ride quality. The massive Brembo calipers and large rotors coupled with steel suspension arms and cast iron spindles/hub carriers are nightmare enough as far as unsprung weight goes. There is no need to add extra unsprung weight and extra rotational moment of inertia.

exactly this. I would avoid run flats at all costs

 

[Kazz]

The heavier your wheels and tires, the worse your car performs.

 

[rooSTer]

The heavier your wheels and tires, the worse your car performs.

Very true. We should remember that from the Fiesta days lol.