Practicality of wider tires
 

I only recently found this YouTube channel all about tires. Real tests, to the point, clear results. I like it! I watched this one and also the one about the newer Pilot Sport 4S vs Pilot Super Sport so far.

https://youtu.be/Bgz0qF3CuNA

Of course it all depends on power, and not upsetting the balance of the car.

mike_ekim1024: yeah, i like reviews of this guy too. For example also https://youtu.be/ovwopvZLuNc .
As for one about tire width .. you forgot to mention intended use. One thing is for track junkie, another for just very few trackdays per year, another - for someone daily driving on public roads only. For example - importance of wet grip is different then.

wow, he liked the square setups! What a shock!

Being new to the scene I note that a lot of people are running fairly wide tires. Having just bought a BRZ tS, I wonder why the STI engineers went with Michelin Pilots 215's /18 when everything else I see are running substantially wider. Is the stock power of the car a consideration of rolling resistance vs power available?

Any thoughts?

Interesting conversation starting point.

firekat: my bet would be on lowering grip by purpose to ease power oversteer even .. with stock lack of power, and for more fun of feeling driving at limits even at legal speeds. Also twins are rather light, so don't need as wide tires as eg. some heavier bmws or musclecars. As sidegain - also better economy and longer lasting tires, but main purpose was as above, due targeting car for youth / some predecessor AE86 legacy / popularity as drift car (at least in image).
From those that go for widest tires possible, i guess 9/10 do so because they think that adding wide tires "like on supercars" they will never afford will make it closer to ones, or to lesser extent some that don't know how to deal with any loss of grip and just try to throw as much grip as possible. Rest, 1/10, do so to maximize lateral grip in auto-x within class limits, or for more grip if installed forced induction.

I agree with Churchx, 215s keep the car playful. In general, go wider as power increases because of the negative effects on increased weight. Also don't forget cost, skinny is generally cheaper.

Tires are always a compromise. Keep in mind your specific circumstances when purchasing.

On paper an all season might be close to a summer or summer close to a track oriented tire. But get some heat in them, more than a 40 second autocross track. Then see the real differences.

Unless you track your car or add FI, going wider than stock adds nothing to performance and is worse on wet roads. Upgrading your tires from OEM does make a much bigger difference (which is what I did on a new 2018). Those who do it are, for the most part, supercar wannabes -- or worse, ricers. Yes, those wide tires and low offset rims do look sexy. And yes, I did this kind of stuff when I was young, i.e., intakes, exhausts, headers, wheels/tires. The difference? I've now owned supercars and know the difference. Also, every time I hear an inexpensive car with a loud exhaust, I think "ricer". The exception are those who race their cars and are looking at every minute improvement.

Wide tires is the current trend, but keep in mind that the first WRX RA's and WRX STI RA's had 205/55 tires and power up to 280ps with turbo. A stickier tire on stock wheels or on lighter similar size wheels is all you need, unless you go more than 300ps.

Check here: http://www.type-ra.com/impreza-type-ra-specs/

True but they probably weren't 205 width Ling Long Ding Dongs

While I agree with the sentiment, the RA (record attempt) cars aren't specifically showing what record they were attempting to take. (may be public knowledge, I just don't happen to know, sorry for my ignorance) With the weight and frame of those cars, coupled with the AWD and an LSD in the read, surely they had no traction problems even at those power levels.

Don't discount that different weight and chassis size/balance on a car will very much dictate generally what tires you'll need for a goal. I can say that a 200tw tire in stock size is way more than enough grip at stock power levels, you'll be hard pressed to lose traction unless you're trying.

TL;DR - For this car frame, I completely agree that stock size or a 225 will offer completely more than enough grip if you go with a good tire and have it inflated correctly. I really hate when people buy a discount 255 section tire and complain they still have no grip...this is why some people just don't know any better I think :(

Even more relevant are the new WRX's. They use 245's for 268hp plus in a car that weighs 3400 lbs while the BRZ's come with 215's for 205hp and 2800 lbs. When racing, there is no need to go much wider, only for track tires which are far more sticky. Again, if you are going to FI your car, there is an argument to go 245's on the rear, but given the light weight, even that is a push.

A lot of people go for 245's/255's etc. for looks. Wider tires look better, even though they may perform the same or worse. For most street driving it's all fine, no issues with skinny or wide as long as you have clearance.

So, while thinking about this thread, I'd like to present a definition:

https://www.urbandictionary.com/define.php?term=ricer

So what percent of "ricer" are you? I went up from 215's to 225's, so I'm probably 5% there.... I could argue that these are much better tires, which they are, but I could have put on 215's.... Oh, well.... Here's a proposed list:

Add an intake -- 10%
Add headers/exhaust -- 20%
Lower car -- 10%
Wide tires (235+) -- 15%
Expensive rims -- 20%
Big spoiler -- 15%
Stickers, etc -- 10%

Shoot I'm at 45% already, only reason I'm not at 65% is I'm too cheap. And I'm a 46 year old caucasian dad with 2 daughters living in Westport, Connecticut.

Great, and you've increased MY rice by selling me your wheels ( that are fantastic, thank youuu). I don't think headers should add to your rice level,. it's a proven modification since engines were a thing... the noise change, however..

Width and grip are not correlated when looking for outright performance.
This has been debated many times and proven over and over (there’s a few good YouTube videos explaining this somewhere).
Grip comes primarily from tyre compound. Wider tyres of similar compound will generally last longer, but will not do much to add grip when cornering etc.

Toyota has said many times the OE tyres where chosen for fun (and probably cost and longevity).

Most people seem to think wider = grippier for some reason, but I reckon the trend is more to do with looks. Particularly on street cars.

Width and grip are not correlated when looking for outright performance.
This has been debated many times and proven over and over (there’s a few good YouTube videos explaining this somewhere).
Grip comes primarily from tyre compound. Wider tyres of similar compound will generally last longer, but will not do much to add grip when cornering etc.

Toyota has said many times the OE tyres where chosen for fun (and probably cost and longevity).

Most people seem to think wider = grippier for some reason, but I reckon the trend is more to do with looks. Particularly on street cars.

225 is good choice on twins for practical reasons. To up grip for those that really need (as it's still too narrow for those that are after arguable looks), not requiring spendings on wheel upgrade too, and by chance 225/45/R17 are also much cheaper/more common tires then of our stock size.

So are you giving me a break on my 5% for getting 225's? I appreciate the effort.... (The 215/45/R17 PS4S was both available and cheaper, by the way).

So are bunches of things done to race cars. The only mods I can give no rice credit to are adding FI and improving the braking if you drive aggressively. I think the appropriate rice level for me is about 10% -- which means I've got 5% to go.

The real problem is that there is this constant voice in my head saying, "bigger wheels/tires, headers, exhaust, big exhaust tips, lower the car, etc." Perhaps we should write an essay on "The Ricer Within.....".

There's also a weight difference between the first RA and the current RA of about 800lbs.

I would not put 205s on my current STI lol

Hey! Glad you're enjoying them, and happy they are increasing your rice factor :D

I went through a phase where I was all about "maximum optimized performance" blah blah. Then I realized that it's a moving target. Stock tires are fun, and great for learning. They have some pretty undesirable characteristics, but the way they chirp, squeek, squeal, and complain under any sort of duress at all proves to be a great learning tool. Stock suspension could use a better compound. Upgrade your suspension and you really need a better compound, and possibly slightly wider tires. Change to 18" rims you're likely increasing unsprung weight/rotational mass. On and on. But - I like my coilovers not only for how they handle, but how easy they are to adjust, how nicely they dampen over weird imperfections in normal driving. I love how my 18's look & how they fill the wheel wells, despite their weight, scrub radius yadda yadda. I love my ride height, even though it's low enough to negatively impact my handling. On the street, my car without a doubt handles better than stock, and more than I'll need in 99% of my driving. I realized I'll get more personal enjoyment out of the aesthetics and I won't miss any subtle negative change in performance. YMMV :)

Yeah I agree with moving target. After having over built previous cars' suspension, I'm only doing eibach pro kit, alignment, these wheels with decent tires and turbo. If you take all the roll out of the car, you end up driving faster until you find it..

Maybe US thing or particular tire model thing? (PS4S not sold in EU of 17" & 18" sizes, only PS4). But most tires i looked upon, summer or winter tires, PSS, PS4S, AD08R, RE71R, Xice3, Hakkas 7,8,R2, usually were 15-20% cheaper in 225/45/R17 vs 215/45/R17. If tire set lasts for me for 5-6 track days, noticeable savings, if i have to pay 100eur less per each set.

I'm an American... Nobody from another country has a valid opinion.....

Kidding aside, it probably has something to do with supply and demand. I've generally found that bigger tires cost more with only very few exceptions...

I've recently upgraded to 225/45/17 conti extreme contacts( similar to Pilot sports 4s) from 22k miles on stock primacies. Drove over 1000miles the day after they were mounted for a road trip and have driven around town on normal routes for about two weeks now. First thing i noticed...who moved my seat up? crank side handle down...nope. LOL! It raised the car up enough to throw off my perception...now I'm thinking I need some yellows. Second thing i noticed...who messed with my steering wheel? Feel has changed drastically. Its a little numb and has more weight to it. Feels like the wife's 2018 civic hatch with 18's (235/40/18). However, it has way more grip than it needs up front. Rear still shudders when I drive it from standstill, but it's much less than stocks and rear end doesn't break loose at any time now. very stable feel. Third thing I've noticed...car rolls over a little more than before on hard cornering. fourth thing...mpg's have dropped by about 2-3 (about 30-50miles less per tank) from what I could tell on a long trip I took vs same trip a couple months ago. Fifth thing...This particular tire has 7.6inches of tread and is mounted on an 8in wheel. side walls are almost vertical and look very good compared to the stocks which have an almost 45 degree stretch to its 7in tread on 8in wheels. Overall, I like the stability and the amazing comfort and quiet these tires provide, but I think a max performance tire is probably too much tire for these cars stock. I'll probably go either to an ultra high performance or keep the 215/45 next time...

Or maybe even think of going down to a 205/45/17. This is a good mention of the things people don't talk about when going with bigger tires. For daily driving you just have no need for wider tires. The same tires in a smaller size would probably feel better to you and most people, but they want wider tires for looks and don't realize that compound matters much more than size right up until you are looking for that last second or so on track.

That's because you went almost a half inch taller .4" with that size. If I ever go wide it will be 245/40/17 will keep the diameter ~the same

Grip in a straight line? Probably not. But a wider tire, of equal compound, will always give you more lateral grip, provided you can overcome any negatives associated with weight, drag and get them up to temperature.

RayRay88: except if on wet. Wider tire will always aquaplane at lower speeds due need to pump more litres of water out of way. And in winter or on gravel/mud, when skinnier tire has more chances to dig through to grippier surface due higher pressure per contact patch. For daily driven car (even more so - driven year round at any weather/season) i'd rise importance of wet grip by few notches.

I agree 100%, its just that people confuse all the factors associated with tire size choices and just conclude that wider tires do not give you more lateral grip. That in it self is a false conclusion.

People saying that for track usage, in the dry, wider tires do not give you more lateral grip (tire compound staying the same) are the reason shit spread. You either havent tested this yourself and are just spreading lies, or you tested it but are incapable of properly extracting the maximum potential of the car. Also, people assuming better lateral grip is always going to give you better lap times...

Im tired of all this ...

Sigh, https://youtu.be/3X2NbToEofw

Yes i went from 45% to a good 20% in the last 7 months :bonk:

I knew it would, but didn't quite know how to quantify what it'd look like or what to expect as for the feel and other factors. There was a sale so I went for it. LOL. IF anything, I've been clearing bumps and driveways/inclines I'd scrape the stock bumper on even with the new HT autos lip I installed recently. :)
Roads are horrible around these parts so the extra height is nice in that respect. Just have to get used to the lifted eye level feeling...ugh. I miss the go kart eye level.

That video is totally useless. It’s a bunch of stopping distances on a bunch of different cars with different tires and sizes. Sure he draws a lose correlation but it has nothing to do with lateral grip. A skinnier tire will give you more front to back grip hands down. Not arguing with that. See funny cars. But lateral grip is a different story.

Dude. I’m not gonna get into an internet argument with you. Google some stuff... I too used to think wider = more grip. Then I watched and read some stuff... educayshun teaches you to read good and about stuff. Do it.

If anyone is really interested;

However a rubber type is a lot softer than metal, and a road is a lot rougher than a metal plate. Even at low loads the tyre deforms to key into the irregularities in the road, so increasing the load has a lesser effect. That's why you get the sub-linear dependance described in the Wikipedia article.

And anyway, if by "grip" you mean grip when cornering, the grip isn't just controlled by the contact patch area.
...the reason why wider tires are chosen is because they last longer than thin ones!


Italics cos it’s quoted from a couple of sources and not my original words.

https://en.m.wikipedia.org/wiki/Tyre_load_sensitivity

Wider DOES = more lateral grip (to a point) when you account for everything. It isn't as simple as arguing that the contact patch is the same. Otherwise people wouldn't be running wider tires in autocross events.

Also, Engineering Explained annoys the shit out of me. He does a great job of explaining some fundamentals, but his tests are never anything CLOSE to properly scientific. I wouldn't mind that so much if people understood this, but instead people treat his test results like gospel, whereas any proper researcher would LAUGH at the suggestion that his test results were truly accurate. It isn't his fault, as he doesn't have the resources to do a proper test, but that doesn't mean we should just ignore the fact that some of his tests are almost silly in how unscientific they are. They're just meant to be interesting tests that attempt to get some sort of standardized result, but they're FAR from accurate, and they are always hawked as the be-all, end-all of a debate.

The video you linked is a particularly egregious example.