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Anyone consider using run flats to save weight?

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MN
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#1
Most luxury cars these days use run flats to avoid putting a spare tire out back, anyone consider this when shopping for new tires?
 
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OH
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What I Drive
E46, ZE132, C6Z06, Z34, GSX30, CKGT
#2
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.
 
OP
E
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Thread Starter #3
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.
 
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#4
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
 
Messages
147
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79
State
IN
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What I Drive
2018 Kia Stinger GT2, 2004 MSM
#5
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

500 Posts Achieved
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What I Drive
2018 Micro Blue Stinger GT2 AWD
#6
The heavier your wheels and tires, the worse your car performs.
 


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