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...