Question on Tire Size for Stock Rims
 

Hey everyone, im looking into getting a new set of tires for the stock 17’ rims that have 215s on right now. I want something beefier so the rear wheels are almost flush and for a little better cornering. Any suggestions?
For instance 225s on all four corners, or are 245s possible?

I put 225 PS4S's on my stock 7" rims and like the results. The understeer was gone and it tracked very well on corners. The ride was also slightly improved over the stock 215 Primacies. There is a slight difference, however, in the speedo as at 60 mph you are actually going about 61 mph. I can live with that. Those rims are too narrow for a good fit with 245's. In addition, putting on 245's will not give you any better performance. The big difference is the quality of the tire. The PS4S is a much better performance tire. I chose the 225 over the 215 because the PS4S tends to have a slightly narrower tread width than the Primacies. Given the fit of the 225's on my rims, I certainly would not go wider.

Yes, 225/45 will work, and as a stop-gap solution, it is not bad. But if you want wider tires, you need wider wheels to be optimal.

I just got 215s for my 8" wheels. Because, IMO the wheel was not wide enough for the 225s I had.

Tire manufacturers have specs for rim width for particular tires. Michelin says you can SAFELY install their 225 PS4S tires on 7-8.5 inch rims. In fact, their specs are based on installing 225's on 7.5 inch rims which is the optimal rim size in their opinion. Installing these 225's on 8" rims is not even questionable so I don't understand where you would get such an idea. Wider wheels/tires deliver virtually no performance benefit over 225's and in most cases are solely installed because owners like the way they look.

Ok. Cool.

OP asked about sizes, I gave my opinion based on using different tires on different wheels on my FR-S. I have read the manufactures suggested range.

OP a 225/45 is not going to flush out the wheel because it has a +48 offset. Spaceres will; with the stock wheels and tires. +15 to +25 front and +20 to +30 rear is what guys are running on stocks.

OP has 17x7 wheels, so your information was incorrect. Flush is in the eye of the beholder. IMO, spacers on the fronts make the wheels poke a bit. Same is true for 20mm spacers on back. Assumption that a wider track in this car improves handling is just plain wrong. 225's will give him a slightly beefier look without spacers. Spacers may also require a camber adjustment which he may also not know.

You should also have 17x7 wheels, so if you did read the manufacturer's range, you'd know.... Perhaps you can show me the spec sheet you referenced for 225's and 7 inch rims.... I'm always open to learning something....

:sigh: I never talked about assumptions; You assumed that I think spacers are a performance mod. You are incorrect.

They just flush the wheels out. And if your opinion is that it makes them poke, thats totally cool. But many forum members do not feel that a 225/45 flushes out the stock wheel, and thats why they run spacers.


I have had over 60 tires on my FRS already, and my opinion is that a 17x7 is not wide enough to optimally run a 225/45. And since OP mentioned 245s, I know he is thinking about them, so my suggestion to get wider wheels if he wants wider tires than 225 is correct.

My signature, has my current 18" wheels. They weigh less than stock.

You said you had the manufacturer specs -- I guess you don't. Have you ever run 225/45R17's on your FRS? I have them on my BRZ and it's not even a close close call as there is absolutely no pinch. The OP indicated he thought the spacers would make the car corner better, so it was referenced as a performance mod. And for the record, I have no problem with you modding your car in any way as it is your money. IMO, wide 18's with 245's on a 40mm or so offset makes the car look good. But if you are really after performance, 17's are probably better and wider tires are not except in special situations. I have done a lot with my cars on the basis of how they look, so I certainly have no criticism if you wish to do that. I tried to justify getting new rims on my 2018 instead of just new tires, but I couldn't do it on the basis of performance, so I decided not to do it. It was awfully tempting to look at all of the wheel options out there. In my younger years, I did a lot of things like lowering, headers, exhaust, intakes, wheels/tires, hot cams, etc. But at my old age, I'm only willing to mod if there is a significant performance improvement I need in a daily driver. The only one I could justify on that basis was the upgrade to the PS4S's. Lowering the car an inch or so makes it look better, but it does degrade the ride quality and doesn't make the car handle better.

I'm just trying to give the OP an objective answer and not trying, in any way, to degrade what you have done. For us car freaks, our cars are an extension of us. So if it makes you feel good to do any of this, you should do it....

I stated that I read the manufacturer specs. And, yes I have had 225/45 on stock wheels and on 17x7.5 wheels. They fit better on a wider wheel than 7".

You mention in another thread that Michelin was wrong about the factory specs. So you already understand that they can be incorrect. I've stated my opinion about Tire width and rim width. You've added a whole bunch of other stuff in with your assumptions. I understand you want to give OP all the information so he can make an educated choice on what tire and wheel he adds to his car. Thats Great! And some guys run 17x9 with 245, even though YOU think it does not increase performance.

Additionally, IMO, you decided to not get rims on a basis of budget. NO race team uses stock wheels. So obviously, there are better wheels than stock performance wise.


Good luck!



This has been a fun back and forth, I hope you don't feel personally attacked. Everyone is entitled to their opinion, and I have been posting mine here in the wheels/tires section for almost 6 years. Thanks for sharing yours.

Check out my build thread for more info.:thumbsup:

When a manufacturer like Michelin gives a range of wheel widths, I've found that the fit is just fine on their range. Within that range, I'd agree that 7.5 for 225's is a "perfect" fit, but I wouldn't go with less width just because I had a 7" rim. And I wouldn't say to anyone that you shouldn't put 225's on a 7" rim. I can tell you from experience, the fit on a 7" rim is extremely good.

Just because someone runs with 10.5" width rims and 265's doesn't mean it's the best performing setup. In fact, there is a lot of evidence that putting anything wider than 225's on the front reduces handling. Extra wide wheels and tires also weigh a lot more. If there were evidence that putting 245's on this car improved performance for a street daily driver, I'd get new wheels and tires in a snap.

While there may be some errors in the Michelin specs, I've found them to be far and few between. And when there is an error, it is a large one like the weight of the 225/45/17 PS4S. That error is really obvious. Over the years, I've never found an error in rim width and I've purchased hundreds of Michelin tires....

Pretty much end of thread with that answer. With the stock wheels, spacers are the only way getting "flush".

To OP: The spacers on stock wheels thread in here http://www.ft86club.com/forums/showthread.php?t=59838 is what you seek.
Also bunch more here:https://www.google.com/search?q=spac...w=1920&bih=949

So to get this straight and settle it. I have been looking at getting 225s on the front and 245s on the rear with these exact tires and stock rims. Looking at the feedback that wont work and or wont fit? (I know some people will roast me for looking at Firestones but I have had a set previously and the reviews are also very good compared to others) --> https://www.tirerack.com/tires/tires...I5XL&tab=Sizes

Yes that will fit no problem, but putting staggered tires on this car isnt ideal from what I've read around here. I have no experience with staggered setup on this car so i cant say much. No one is going to roast for those tires those are very well acclaimed tires and people will praise you for getting them.

I just know in the car community firestones aren't looked upon too highly. From what other responders have said 245s on all four corners isn't the best idea. This may be a dumb question as im not super knowledgeable on tires, but wouldn't 245s on all four corners be better than 225s from a performance perspective as long as everything fits just fine?