235/45r17 vs 225/45r17?
 

I know this is a tire question but I was hoping for answers more specific to handling on track. I apologize if this really does not belong here and won't be offended if the thread is moved.

I'm looking at Hankook RS4s for the coming track season. Last year was my first season of autox and hpde events and I did all of them on a set of Conti ECS 225/45r17s mounted to 8 inch wheels. They still have life in them but I'm interested to try new tires and know I'd need to replace the Contis before the end of the season anyway.

My question is whether I would be better off on track with the 235/45r17 or 225/45r17 RS4s. Ideally I would like a 235/40r17 but the RS4 is not offered in that size. After looking at everything on a tire size calculator I have some concern about sidewall flex/weight/general vagueness with a tire that much larger, maybe even mild rubbing issues with my TRD springs?

I feel like the 225 is likely the correct choice, but I may just be overthinking everything and the 235s would just work fine and outperform them. I don't want to hurt the overall feel of the car but I am looking to pick up a tire that is noticeably more capable. Any insight here would be greatly appreciated and I thank you in advance.

I have very good experience with 225 45 17 Falken Azenis, they are offered in 235 40 17 but they are more expensive.
IMO, I prefer 235 40 than 235 45

I haven't tried 235/45, but just some thoughts with my comparisons of 215 and 225. Since they are all 45 aspect ratio, the 235 will be a taller tire and effectively make your gearing slightly longer. If you have a 2017+ with the higher ratio diff, that may be ok, but if you are 2013-2016 you are probably heading towards a gearing disadvantage.

Another thing I found is that tire weights change drastically between sizes in order to meet load ratings. I found that 225s ran heavier than 215s, and combined with some tire models being heavier, you could have significant rotating mass that can hamper acceleration. Usually a sticky compound can overcome the deficit with cornering speed, but I saw a measurable effect.

225/45R17 is a also very common size, which means there are more options and they tend to be will priced and well stocked. Unless you are stepping up to 245, I found them to be the sweet spot.

I had 235 45 17 rs4 mounted on 9in wheels and they ate my front fender liners. Car was set to maximum height on the RCE T2 and pretty stiff settings. It shredded the front and top of them and had to cut them off so they dont flap aroud in wheel well. I am planning to run 225 45 17 for DE to keep costs down this year.

I have 235/45 17 on 8" +45.

Fit well, lots of clearance even with a 20mm drop from STD height.

I prefer a bit more side wall and will compromise some performance to achieve this.

A 225/45 17 on a 8" rim would fit better and possibly perform better though.

And you cannot go wrong with the Hankook RS4 IMO, great tyre, great price.

What are your front end camber settings and offset of your wheels? I have almost the exact same setup as you (RCE T2's, 235/45/17 RS3's on 17x9 +42 wheels, -2.5* front camber) and haven't had any issues with rubbing in either track or street driving.

Re. the thread topic, my track tires before these were 225/45/17 BFG Rivals on 17x8 wheels. 235/45 vs. 225/45... it's very hard to give a comparison without controlling for tire differences, but the 235 setup has a bit more grip in corners. Also a little softer, which is better for street driving, worse for track. Lastly don't forget the 235 setup will lengthen your gearing a little.

It was -3.5 front -2 rear 0 toe all around. My wheels were +38 offset. I was running a 7 in monster splitter when it happend maybe that was the issue. Last season has been fine with my splitter shortened to 4 in and with 255/40/17 ar1 and conti ecs.

If tirerack.com is correct. Then the 225/45/17 RS4 has an OEM diameter, and the 235/45 has the diameter of a standard size 225/45. I don't see the 0.1" additional tread width of the 235/45 being an advantage because it's 2lbs heavier than the 225/45.

Yeah that's interesting. -3.5* is a fair amount of camber and the offset of your wheels isn't too crazy. I have no idea why that setup would have had rubbing issues. :iono:

I also have RS4s at 235/45 17 on 8" +45. No issues on stock suspension, one track day so far. I would have gotten the 225 size but it was unavailable at the time, I doubt the 10mm would be much of an advantage given that it's so grippy already. I've been dailying it and it is much more comfortable.

Ignoring parameters like cost/fuel/fitment, if chasing a laptime is the objective, then the debate between smaller width and larger width tires (+- ~20-30mm) comes down to a pretty simple question:

In what case do you want less cornering speed?


Anecdotally from Texas and south region 86 competitors, they've found that any loss in straight line speed from increased rolling resistance is negligible compared to the cornering speed gains a proper driver would achieve from wider width tires.

i will be the devils advocate here and put a word of caution

if you cant use the full width offer by a 235 i would stick to a sticky and cheaper 225

I autox in a street class ( or stock now..) and use a 225 45 17, and still am lapping faster than some guys in STX or STU with 245/255's

now the difference would be greater on a bigger track yes, but if you arent utilizing the full benefit of the wider tire, then having it is just extra cash thrown at something you arent using. and a smaller tire will teach you more about a car than a wider stickier one.

Something along the lines of "learning to drive the car" over driving with the tires. In the rallyx world we have to depend on skinny 185's and tire friction is always assumed low, and we use body roll, momentum and weight transfer to corner the car. this translated back into tarmac driving with somewhat good tires


Now back to the OP

The 235 45 17 is a rare size. I would look at upgrading the diameter to 18s possible an 18x8 or 18x8 and going with a 245. at this point the offset becomes more crucial as the stock struts do stick out a bit.

its one of those rabbit hole deals, once you start reengineering the car, you have to start changing other small things.

I wanna see what you come up with and tell me your thoughts as you enter this next season....
all my events for the this month have been canceled >_>

RE:driver, this is fair and why I said a "proper" driver. In all honesty, a novice driver should start to as close to stock as possible!

Although some people prefer to choose the "cash mod" method of improving lap times, instead of the "driver mod." We all have our choices :iono:

there is some truth to it. that said i wouldnt lap on stock 215 primacies hahahaha rolling around on hockey pucks...

I literally just did that at a local event yesterday. Hockey pucks indeed, though it was a car control day for me so I wasn’t bothered. Quite fun, but quite slow. Lol


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I really appreciate all of the input in here! I think I'm leaning heavily toward the 225/45 RS4s for this season. Comparing the specs side by side, it looks like I'm only giving up .1" of tread between the 225 and 235, but compared to the ECS I ran last year the tread is around .5" wider despite them both being 225s.

I feel like it's worth giving up .1" in order to save 2lbs per wheel and preserve near oem wheel size. Next year I may spring for bigger wheels and make the jump all the way to 245 when I'm not also spending on an oil cooler, camber plates and a helmet lol

A lot of my concerns ultimately boil down to more sidewall dulling the super sharp steering feel that I love about the car, and potentially crossing a threshold of grip that pushes the car back toward understeer. I want the car to be fast, but I also want it to feel lively and engaging to drive. I understand that if I keep pushing toward pure performance I may have to make a compromise there, but I'm not at that point yet. I feel like for this season sticking to a similar tire size will give me the best frame of reference for how the alignment and new compound are working. This is still very much my learning phase and I'm not banking on being involved heavily in actual competition yet.

Thanks again for all of the responses, and keep them coming if you've got more to say!

Well it's miles too tall, so that's probably why.

Primacies are fine for beginner drivers. Learn car control and slip angle at slower speeds and cheaper cost. My normal path for most drivers is to start on Primacy, move to 300ish tw like an Indy FireHawk 500, then 200tw. Has seemed to work out for them well compared to those drivers that move up too quickly then soon plateau.

Track is probably a little different.

For autocross, it is really easy to develop bad habits on crappy tires, as it often takes some pretty extreme and unorthodox inputs to inspire a car with incredibly low limits to rotate.

thats interesteing you say that

I daily on firehawk indy's and my autox tires i upgraded from federal RS-RR to Kumho V720s and I just got like two days ago a new set of Potenza RE71RS for this season.

to be fair the only reason i had the firehawks is cause i got 18x7.5's and then thought better of it and got another set of PP rims for autox purely.

and I agree with the above guy, driving with a weak tire, with little to no skilset, can develop bad habits. now having driven on better tires, and going to a few control clinics, and going back to the primacies makes it fun. and almost a unique challenge. you get back into a rallyx mindset with how to corner.

This is entirely backwards of anything I have experienced :iono:

Crappy tires are good for learning car control.


Crappy tires are not necessarily good for learning the car setup or the finesse that you need to be competitive on the top tires for your class. The limits are sometimes so low that it is hard to learn much about getting close to those limits.

And this I agree with 100%. :iono:

If you're trying to follow the straightest line, when are you being taught otherwise by the grip of the tire? If you're unable to hold the line you want, you don't develop the ideology that straight isn't fast suddenly.

I get what you're saying here, but I don't think using weak tires will teach bad habits, it just gives you a ceiling to hit. It's like anything else, eventually, all parts are sum of the whole. Once the driver stops being the weak point, you upgrade accordingly and slowly raise the ceiling.

The biggest thing I have noticed on some of the lower tier 200TW tires is their breakaway characteristics make it hard to learn to drive the tire up to the limit, the Hankook RS3 comes to mind. Crappy tires I find easy to drive to the limit.

235/45r17 vs 225/45r17?
 

Think about what you just said there...the “limits” are too low to learn much about getting to the limits”?

Using crap tires is great for learning or honing skills. Doesn’t matter if you’re a beginner or professional using good or bad tries...the driving fundamentals are the same. How you use them to accomplish the goal of weight management is also the same.

The tricky part is learning to “fill the circle” while at maximum loads available. Obviously this is easier to do if the limits of the tire are lower as you will spend significantly more time exploring the limits. More often then not, a less grippy tire is going to require more finesse and smooth operation than a sticky tire, as any mistake you make is going hurt your momentum that much more. A proper tire will tend to mask the wound of unrefined driving with the bandaid of grip.

However, I’m in complete agreement that you will never find the correct setup for a sticky tire by using a crap tire. You always setup your suspension to maximize the tire, so if you’re constantly changing tires, or using tires that are completely different in scope you’re going to have issues.


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Hard tires break loose at lower speeds. When you start driving, tires breaking loose, especially rears, is a scary situation. You want to be scared at 45 mph and not 90 mph. Once you're comfortable with catching and correcting oversteer at low speeds then you're ready to progress up the tire ladder and not before. The inputs will be the same however the breakaway speeds will be different.

You know you're comfortable with catching and correcting oversteer when you have someone in the car and you can carry on a conversation while catching the slide. Skidpad time is your best training tool

Where/how did you get teh RE71RS? I though they werent coming out of Japan till next year?

RE71R's

phone musta been all excited.


I want the RS.... lol

RE-71Rs*

No....no you don't