A question about OEM tires

[RToyo86]

Originally Posted by ZDan

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.

235/40r17 = 24.4 (-0.8%)
215/45r17 = 24.6
245/40R17 = 24.7 (+0.4%)
225/45r17 = 25 (+1.6%)


235/40 is closer than a 225/45 in height.
I agree 235 isn't Ideal for an 7.5", it's at the max end of the spectrum.

[ZDan]

Originally Posted by RToyo86

235/40r17 = 24.4 (-0.8%)
215/45r17 = 24.6
245/40R17 = 24.7 (+0.4%)
225/45r17 = 25 (+1.6%)
235/40 is closer than a 225/45 in height.
I agree 235 isn't Ideal for an 7.5", it's at the max end of the spectrum.

235/40-17 is too wide for a 7.5" wheel, minimum recommended width is 8", max is 9.5", measuring rim width is 8.5".

I just looked at eight of the most popular max and extreme performance tires in 215/45-17, and six of them were 24.7" in diameter, one was 24.6", and one outlier was 24.4" (Hankook RS4). Also OEM Primacy HP is 24.7" in 215/45-17, so stock diameter is 24.7".

225/45-17 is a very good fit on 17x7.5 and very close to stock diameter. 235/40-17 is not recommended on 17x7.5 and is as as much shorter than stock diameter as 225/45-17 is taller. Which is not enough to be concerned about anyway...

[Racecomp Engineering]

225/45/17 works really well on this platform with a 7.5 or 8 inch wheel. There is also a wide selection of tires to choose from.

- Andrew

[qqzj]

Originally Posted by Racecomp Engineering

225/45/17 works really well on this platform with a 7.5 or 8 inch wheel. There is also a wide selection of tires to choose from.

- Andrew

Any tire you can recommend? Is there a relatively lighter one?

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[TunaNoCrust]

Originally Posted by qqzj

Any tire you can recommend? Is there a relatively lighter one?

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Really need to know your end goals. What are your most important criteria?
Tread Life, traction, noise, etc and will it be tracked, driven in snow, temperature range?

A lighter tire?

[Racecomp Engineering]

Originally Posted by qqzj

Any tire you can recommend? Is there a relatively lighter one?

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Daily driver? Looking for an all-season or a summer tire?

- Andrew

[venturaII]

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.

To add to the murkiness, that number is calculated when the tire is mounted on an 'optimally' sized wheel...so, the measured section width and tread width will change, depending on how wide the wheel is. Ever wonder how TireRack comes up with the range of acceptable wheel widths for tires, and then the one they use for their published numbers?

As far as what actual tire to recommend, given that you're in California, I'm assuming you could get away with a dedicated summer tire; certainly a high performance all season one. I think Continental make excellent tires that perform 95% as well as the benchmark Michelins, but for far less money. Additionally, Contis always seem to be the lightest in their category, at least in the extreme summer and winter categories I've used in the past... Some complain about them having a softer sidewall than others might, but I don't feel it's to the overall detriment of the tire; response might be incrementally lower, but unless you've got urethane bushings everywhere already, I think that's chasing handling perfection in an already compromised system.

[TunaNoCrust]

Originally Posted by venturaII

I think Continental make excellent tires that perform 95% as well as the benchmark Michelins, but for far less money.

I entirely agree, great performance to price ratio with Continentals, especially since their Hoosier acquisition I feel.

[qqzj]

Continental has many tires with suitable sizes. Anyone you can recommend? Dws06? Control contact? Thanks

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[strat61caster]

Do you go up to Tahoe with the car or just stay in the Bay?

If no snow have fun and get the Extreme Contact Sports, very highly rated tire, will do great year round here.

[qqzj]

Thanks. No ski trip with BRZ. I have MDX for that.

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[ROFL it's Waffle]

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 kind of feel like this has something to do with sidewall rigidity, like what you'd see with all season tires (tire might be flush with rim) vs summer performance tires (tire may extend beyond the rim).


Do the OEM tires come with all-seasons, or is it more performance oriented? I've always wondered if the "Prius tires" was just the same dimension, or the actual rubber that ships on the Prius too.

[JD001]

FFS.... Meaty tire thread in disguise... makes my head hurt.. BTW, I still haven't got round to switching my OEM tyres!! Coming up to 5.5yrs.. circa12.5k miles.

[conehead]

Originally Posted by Mr.ac

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.

Posts like this drive me nuts. If you are going to be condescending and sarcastic, at least know what you are talking about.


The OP is absolutely right. Tread width and section width are different, and the section width is just a rounded off number on a sample size wheel anyway. Tires with the same advertised section width can have a range of tread width, and efficiency tires like the primacy tend to have narrower treads and hard rubber to reduce rolling resistance and increase MPGs slightly (which OEMs like for certification and advertising). Performance tires are the generally opposite.


Stretching tires onto wider wheels is common in race classes that limit tire section width. It maximizes contact patch and minimizes tire rollover. Race classes that limit wheel width tend to do the opposite and stuff the widest tire they can on the wheel.