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2021 Forester Premium
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Discussion Starter · #1 ·
Sorry for the long title. Do the Subaru engineers build the suspension around a specific tire. Or is that just Porsche / BMW thing?
 

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2021 Forester Limited
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To a point, they probably designed the damping rates of the struts for the tire wheel combo, in addition to the spring rates and vehicle weight. But given how many folks have went with different sizes, and have not had drastically bad things happen over any other like vehicle with the same changes, I would say no.

These are not that complex. The price would be $30,000 more.
 

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2022 Forester Sport
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148 Posts
I reckon the accountants build it to a certain price ;)
I agree. Subaru purchasing department seeks bids for 'x' number of tires and low bidder wins.

If tires were a design factor, there would not be thousands of posts, across all Subaru forums, complaining about the quality of the factory tires.

My wife is on her third Forester, each came with a different brand of tires, and all were just fine.
 

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Discussion Starter · #5 ·
I agree. Subaru purchasing department seeks bids for 'x' number of tires and low bidder wins.

If tires were a design factor, there would not be thousands of posts, across all Subaru forums, complaining about the quality of the factory tires.

My wife is on her third Forester, each came with a different brand of tires, and all were just fine.
i asked the question because I thought —naively, I admit— the whole question about the best tire for the car could be answered by knowing what tire they used to tweak the suspension.
 

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They probably take into account the average weight of tires in the size they choose, so the struts will control the unsprung weight effectively for whatever brand the consumer installs after the sale.

There is probably a generous amount of wiggle room factored in.

But I wouldn't expect it to control a tire/wheel combo that is 30 pounds heavier than the originals.

Bottom line, if you increase/decrease the tire size and weight significantly, expect things to change proportionately, and adjust accordingly.
 

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2012 Forester X Auto
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The "designed for a specific tire" in street applications is typically because of very high performance (speed) considerations.
Most passenger cars aren't capable of the Bugatti Chiron Super Sport's theoretical 304 mph (it's got a governor for 273mph) and that car can't achieve that speed with a set of all season radials which would shred getting there.
Even for this car, the manufacturer went from a specific tire design in the Veyron at $30,000 - $42,000 per set to standard mounting, but then chances are you would have to special order the 285/30 R 20 (F) 355/25 R 21 (R) rubber as most service stations won't have them on hand. ;)

It's not that Subaru manufactures a car for a specific tire, it's that some tire manufacturers produce tires appropriate for a Subaru.

A Forester, like most other passenger cars, needs tires that have an appropriate size, weight rating and design for its intended use to work well, which in the case of a Forester can vary by driver.
Commuter and off-road drivers won't want the same tires.
Performance in hot dry states and cold wet ones won't be optimized if they used the same rubber.

The Chiron on the other hand is made to go fast on pavement, period.
 

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Discussion Starter · #9 ·
The "designed for a specific tire" in street applications is typically because of very high performance (speed) considerations.
Most passenger cars aren't capable of the Bugatti Chiron Super Sport's theoretical 304 mph (it's got a governor for 273mph) and that car can't achieve that speed with a set of all season radials which would shred getting there.
Even for this car, the manufacturer went from a specific tire design in the Veyron at $30,000 - $42,000 per set to standard mounting, but then chances are you would have to special order the 285/30 R 20 (F) 355/25 R 21 (R) rubber as most service stations won't have them on hand. ;)

It's not that Subaru manufactures a car for a specific tire, it's that some tire manufacturers produce tires appropriate for a Subaru.

A Forester, like most other passenger cars, needs tires that have an appropriate size, weight rating and design for its intended use to work well, which in the case of a Forester can vary by driver.
Commuter and off-road drivers won't want the same tires.
Performance in hot dry states and cold wet ones won't be optimized if they used the same rubber.

The Chiron on the other hand is made to go fast on pavement, period.
Dang! I was thinking about those low profile z rated tiires😂 oh well I’ll just buy a Kornigsegg!
 
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