A question about OEM tires - Toyota GR86, 86, FR-S and Subaru BRZ Forum & Owners Community

qqzj · 10-01-2019, 08:15 PM

The OEM tire seems to have very narrow tread width. Typically, for the cars I owned in the past, the tire width is larger than the wheel width. So the side wall is overall higher than wheel surface. So I feel like the side wall can help to protect the wheel a bit.

But for the OEM Michelin Primacy HP, the side wall is only taller than the wheel near the edge. This both looks strange. It also make the wheel more vulnerable. This is especially so after I used 17x7.5 wheels.

Does anyone else share the same feeling? Is it called stretched tires? I am just curious, no other intentions. Thanks. The tire is designed this way for the looks or to save gas?

Mr.ac · 10-01-2019, 08:48 PM

Ah you been smoking the good stuff eh?

Let go over real quick tire size.
215/45/17.
First number is tire width. Bigger the number, wider the tire. And vice versa
Second number is side wall hight. Bigger the number taller the side wall. And vice versa.
Last number is rim/wheel size. Self explanatory.

As for your complaint, what you want is a wider tire. A 225/45/17 would be the fix for you. If you want more meat a 235/40/17.

Stretching tires is really a retarded move. Some would say it helps with tire flex, but really they are just retarded. If you wanted performance you'll just get better tires.

As for the idea of design, gas saving, performance, nah it's just the tire companies making a deal with the car company. Some retards would disagree saying the oem tires are a god send. Lol nope.

soundman98 · 10-01-2019, 09:50 PM

what ac missed is that the 2nd number on the sidewall is the sidewall height, indicated as a percentage of the width of the tread. very confusing.

i suggest playing with this to see roughly how anything else will fit.

https://www.ft86motorsports.com/wheelitfit/

you want to avoid running a larger overall tire, as it will alter the indicated road speed, as well as affect final gearing negatively. the car will act slower.

RToyo86 · 10-01-2019, 09:59 PM

Quote:

Originally Posted by Mr.ac

Ah you been smoking the good stuff eh?

The devils lettuce.

--------------------------------

The 215/45R17 is the same tire on the standard 7" wheel.
A 225/45R17 is ideal width for 7.5" but will be taller than stock which is likely why subaru kept the same tire.

235/40R17 is the widest tire you can fit and closest to stock height. It is expensive less popular size.

TDLR they probably did it because it was cheaper and easier to slap the same tire on the PP wheel. 215 is within spec for 7.5".

qqzj · 10-01-2019, 10:46 PM

Nah. Let me explain a bit more. 215 is the width of the tire. The place where the tire is 'widest'. For most of the tires I have seen before, the 'widest' place is in the middle of the side wall, with the width of the tread larger than wheel width.

For the OEM tire, I feel that the 'widest' place is just where tire meets the wheel, with the width of the tread smaller than wheel width.

So the key is the definition of '215'. Tires with the same 215 width can have different tread width for sure.

Leonardo · 10-01-2019, 11:08 PM

While I agree that a 235/40 would be the widest tire for a 7.5" wheel. (Though a 225/45 is probably best)

A 245/40 is the closest to a 215/45.

215/45/17 = 24.6" diameter
245/40/17 = 24.7" diameter

235/40/17 = 24.4" diameter

strat61caster · 10-01-2019, 11:17 PM

It's a low rolling resistance tire, less contact patch than your typical summer tire, I'm too lazy to looks up the tread width specs on tire rack on my phone but go have fun. Yes it's a touch stretched on a 7.5" which furthers the perception.

soundman98 · 10-01-2019, 11:31 PM

Quote:

Originally Posted by qqzj

Nah. Let me explain a bit more. 215 is the width of the tire. The place where the tire is 'widest'. For most of the tires I have seen before, the 'widest' place is in the middle of the side wall, with the width of the tread larger than wheel width.

For the OEM tire, I feel that the 'widest' place is just where tire meets the wheel, with the width of the tread smaller than wheel width.

So the key is the definition of '215'. Tires with the same 215 width can have different tread width for sure.

i see what you're saying. for the tires on other cars that are 215mm width, but have some bulge in the sidewall, inspection of the wheel package should show that they're running a narrower wheel, somewhere near 7"-6.5" wide wheels. by using a 7.5" wide wheel, you're using up that sidewall bulge in a different way.

Overdrive · 10-01-2019, 11:33 PM

Lots of tires these days are made with a little extra edge on the tire's lip to give the wheel's rim a little bit of protection against curbing. It's still possible, but in many and most cases it does the job. It can make some tires look a little odd, but I can appreciate the function behind it.

If you want something wider, why not just get wider, better looking wheels anyway to go along with a wider tire?

wparsons · 10-03-2019, 10:11 AM

Quote:

Originally Posted by strat61caster

It's a low rolling resistance tire, less contact patch than your typical summer tire, I'm too lazy to looks up the tread width specs on tire rack on my phone but go have fun. Yes it's a touch stretched on a 7.5" which furthers the perception.

https://www.tirerack.com/tires/tires...S&autoModClar=

Tread width is 7.5", section width is 8.4"

qqzj · 10-03-2019, 10:18 AM

Thanks. So just want to make sure 225 tire width is the perfect match for a 7.5 wheel? If so, I shall change to 225 45 17 next time.

Sent from my Pixel 3 XL using Tapatalk

DarkPira7e · 10-03-2019, 10:53 AM

This also can depend on your sidewall heights. If it's a narrow sidewall, you're more likely to get a / appearance, compared to a |. If the sidewall is tall and weak, you'll get the ( (look at like a 215/70 winter tire for example)

Honestly, the stock tire sticks out more at the bottom of the sidewall than the top. That's just how it was designed and fits.

Leonardo · 10-03-2019, 11:05 AM

Quote:

Originally Posted by qqzj

Thanks. So just want to make sure 225 tire width is the perfect match for a 7.5 wheel? If so, I shall change to 225 45 17 next time.

Sent from my Pixel 3 XL using Tapatalk

For our cars; a 225/45/17 is a perfect size tire for a 17x7.5" wheel.

ZDan · 10-03-2019, 11:22 AM

Quote:

Originally Posted by RToyo86

The 215/45R17 is the same tire on the standard 7" wheel.
A 225/45R17 is ideal width for 7.5" but will be taller than stock which is likely why subaru kept the same tire.
235/40R17 is the widest tire you can fit and closest to stock height. It is expensive less popular size.

At 24.4", 235/40-17 isn't closer to stock height of 24.7" than 225/45-17 (25.0").
235/40-17 isn't a good a fit on a 7.5" wheel, need 8" minimum up to 9.5".
225/45-17 is a MUCH better size choice for 7.5" wheels.

10-01-2019, 08:15 PM	#1
qqzj Senior Member Join Date: Sep 2013 Drives: MDX, Camry Location: SF, CA Posts: 399 Thanks: 54 Thanked 69 Times in 44 Posts Mentioned: 3 Post(s) Tagged: 0 Thread(s)	A question about OEM tires The OEM tire seems to have very narrow tread width. Typically, for the cars I owned in the past, the tire width is larger than the wheel width. So the side wall is overall higher than wheel surface. So I feel like the side wall can help to protect the wheel a bit. But for the OEM Michelin Primacy HP, the side wall is only taller than the wheel near the edge. This both looks strange. It also make the wheel more vulnerable. This is especially so after I used 17x7.5 wheels. Does anyone else share the same feeling? Is it called stretched tires? I am just curious, no other intentions. Thanks. The tire is designed this way for the looks or to save gas?

10-01-2019, 08:48 PM	#2
Mr.ac [insert cool phrase here] Join Date: Aug 2015 Drives: BRZ Premium Location: Central Coast CA Posts: 2,369 Thanks: 709 Thanked 1,558 Times in 930 Posts Mentioned: 30 Post(s) Tagged: 0 Thread(s)	Ah you been smoking the good stuff eh? Let go over real quick tire size. 215/45/17. First number is tire width. Bigger the number, wider the tire. And vice versa Second number is side wall hight. Bigger the number taller the side wall. And vice versa. Last number is rim/wheel size. Self explanatory. As for your complaint, what you want is a wider tire. A 225/45/17 would be the fix for you. If you want more meat a 235/40/17. Stretching tires is really a retarded move. Some would say it helps with tire flex, but really they are just retarded. If you wanted performance you'll just get better tires. As for the idea of design, gas saving, performance, nah it's just the tire companies making a deal with the car company. Some retards would disagree saying the oem tires are a god send. Lol nope. __________________ New daily driver - Subaru BRZ Premium Weekend fun/track car - '91 MR2 Turbo Gen3 Old daily driver - '88 MR2 Supercharged

10-01-2019, 09:50 PM	#3
soundman98 ProCrastinationConsultant Join Date: Sep 2013 Drives: '14 Ranger, '18 Tacoma 4Dr LB Location: chicago-ish Posts: 11,330 Thanks: 35,240 Thanked 13,673 Times in 6,781 Posts Mentioned: 98 Post(s) Tagged: 0 Thread(s)	what ac missed is that the 2nd number on the sidewall is the sidewall height, indicated as a percentage of the width of the tread. very confusing. i suggest playing with this to see roughly how anything else will fit. https://www.ft86motorsports.com/wheelitfit/ you want to avoid running a larger overall tire, as it will alter the indicated road speed, as well as affect final gearing negatively. the car will act slower. __________________ "The time you enjoy wasting is not wasted time"

10-01-2019, 11:08 PM	#6
Leonardo Country Boy 4 Life Join Date: Jul 2012 Drives: 19' & 06' Ridgelines, 13' FR-S Location: EUGENE Posts: 5,228 Thanks: 6,719 Thanked 5,291 Times in 2,720 Posts Mentioned: 47 Post(s) Tagged: 1 Thread(s)	While I agree that a 235/40 would be the widest tire for a 7.5" wheel. (Though a 225/45 is probably best) A 245/40 is the closest to a 215/45. 215/45/17 = 24.6" diameter 245/40/17 = 24.7" diameter 235/40/17 = 24.4" diameter __________________ I LIKE TIRES!

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10-01-2019, 10:46 PM	#5
qqzj Senior Member Join Date: Sep 2013 Drives: MDX, Camry Location: SF, CA Posts: 399 Thanks: 54 Thanked 69 Times in 44 Posts Mentioned: 3 Post(s) Tagged: 0 Thread(s)	Nah. Let me explain a bit more. 215 is the width of the tire. The place where the tire is 'widest'. For most of the tires I have seen before, the 'widest' place is in the middle of the side wall, with the width of the tread larger than wheel width. For the OEM tire, I feel that the 'widest' place is just where tire meets the wheel, with the width of the tread smaller than wheel width. So the key is the definition of '215'. Tires with the same 215 width can have different tread width for sure.

10-03-2019, 10:18 AM	#11
qqzj Senior Member Join Date: Sep 2013 Drives: MDX, Camry Location: SF, CA Posts: 399 Thanks: 54 Thanked 69 Times in 44 Posts Mentioned: 3 Post(s) Tagged: 0 Thread(s)	Thanks. So just want to make sure 225 tire width is the perfect match for a 7.5 wheel? If so, I shall change to 225 45 17 next time. Sent from my Pixel 3 XL using Tapatalk

10-03-2019, 10:53 AM	#12
DarkPira7e Rust bucket enthusiast Join Date: Feb 2017 Drives: 2013 Turbo Firestorm FRS Location: Vermont Posts: 3,933 Thanks: 3,200 Thanked 4,095 Times in 2,045 Posts Mentioned: 31 Post(s) Tagged: 0 Thread(s)	This also can depend on your sidewall heights. If it's a narrow sidewall, you're more likely to get a / appearance, compared to a \|. If the sidewall is tall and weak, you'll get the ( (look at like a 215/70 winter tire for example) Honestly, the stock tire sticks out more at the bottom of the sidewall than the top. That's just how it was designed and fits.

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