Tire rack video - brz tire width

[Stonehorsw]

[Stonehorsw]

[mike_ekim1024]

Wet lap times were definitely interesting. A little stretch seems to help steering response, and I’ve also heard that. I’m running 8s with 225 and I’m happy.

[new2subaru]

Great info. Thanks!

[Leferd]

Got in on the APEX 17” Group Buy to get their 17x8 and will be putting on 225/45/17’s on them.

[Jianlun]

Wonder what tyre pressures they ran and whether they optimised them before their money lap.

[autosenses]

Originally Posted by Jianlun

Wonder what tyre pressures they ran and whether they optimised them before their money lap.

That's what I'm wondering. I read this test back in Dec. and purchased Tire Racks RPF1 17x8 RT660 225/45/17 packaged. Mounted them this weekend and it looks and feels great.

[strat61caster]

Originally Posted by Jianlun

Wonder what tyre pressures they ran and whether they optimised them before their money lap.

Door pressures cold - 35psi, no adjustments beyond that. It’s in the article.

[Tatsu333]

Just repeating here what I said in the thread discussing the article back in January:

Interesting comparison for sure, but important to bear in mind that different tire makes / models fit and sit differently, so just generally saying X tire width is best on Y wheel width may be over-simplifying things.

The RE-71RS in 225/45R17 is listed on TR's website with a 7.9" tread width, which when compared to a lot of street tires in the same size is anywhere from 0.4-0.6" wider despite the same or similar section widths, so it sits more square / less stretched than they would on an 8 or 9" wheel.

For a more specific example, let's look at the specs of the Michelin Pilot Sport 4S:

• In the 225/45R17 size the PS4S is listed with a tread width of 7.5" with the identical 8.9" section width to the RE-71RS, so with 0.4" narrower tread it would sit and look more stretched on an 8 or 9" wheel.
• When you compare the 245/40R17's in both tires, the measurements converge a bit more - 8.3" tread width / 9.8 section width for the PS4S vs. 8.4" tread width / 9.8" section width for the RE-71RS, so the difference is significantly less.
• Also worth noting that the RE-71RS' measured tread width on the 245's is only 0.5" (12.7mm) wider than the 225's despite being nominally a 20mm (0.79") wider tire.

Now, when compared to another popular 200 treadwear rated tire like the Hankook Ventus RS4, the RE-71RS is more similar:

• In the 225/45R17 size, the RS4 has an 8" tread width / 9.2" section width, so slightly wider in both dimensions than the RE-71RS
• In the 245/40R17 size the RS4 has a 9" tread width / 10.1" section width which is significantly wider than the RE-71RS.
• The difference in tread width between the two sizes of RS4 is actually slightly more than you'd expect, with a 25.4mm wider tread for the 20mm larger nominal size.

NOTE: the measured rim width for the different sizes (7.5" for the 225's and 8.5" for the 245's) is the same across all three tires on Tire Rack's website.

It's also important to consider that some tires may tolerate a more stretched fitment better and have differing performance due to their sidewall construction, where others may not.

Basically, the 225/45R17 RE-71RS is a particularly "fat" 225 (in terms of tread width) compared to the 245/40R17 of the same tire, and compared to most of the more mainstream performance tires (E.G. PS4S and the like), which have much narrower tread width vs. section width.

You may not see the same kind of differences between a 225/45R17 and 245/40R17 Michelin PS4S or Conti ECS, for example. They may not tolerate the extra 0.4" of stretch required for the 225's on a 9-inch wheel as well, for example, and a 245/40R17 may be better on a 9" with those tires.

So - while certainly interesting, the test is definitive only as it applies to that particular make and model of tire. The spec of the tires is more similar to other 200TW tires (like the RS4's), so the results may be more relevant if you're shopping for those than a more street-focused tire.

[Clipdat]

Now this is a man that I could talk tires with for hours. Good stuff.

[ACT86]

Given they were tested on three different cars, I’d be keen to know if they all had an identical alignment. May have missed it in the video.

[autoracer86]

Originally Posted by ACT86

Given they were tested on three different cars, I’d be keen to know if they all had an identical alignment. May have missed it in the video.

I think they had identical alignments. Have a rewatch they should mention it