Going up a tire size
 

Hey guys! I’m new to this forum and to cars as well (just got my brz back in january).

I have a question about going up a tire size/width. As you know, the stock tire dimensions are 215/45/17. I’m planning on sticking with 17in rims, but want to know if there will be any issues if i go up to 225/45/17.

What are the pros and cons? And will it throw off my speedometer?

Sorry if these are dumb questions, I’m such a newb lmao but I want to learn the most that I can! Any and all feedback will be much appreciated!

225/45/17 is fairly common to use. Your speedo will read lower then you are actually going.

per wheel-it-fit.com, changing to a 225/45/17 means the tire diameter will increase from 625mm to 634mm, which would result in a speedo difference of -1.4km/h, which simply means at 60mph, the car will read about 0.5mph slower than actual.

which, my car and others in my families fleet consistently measures around 2mph slower according to speed signs anyways.

idk if im replying to this right but is there anyway to fix that or is it just something you gotta deal with? thank you for your reply!

thank you so much for the reply! i will take that into consideration. a wider tire is grippier correct ?

EcuTec can and I believe OFT will also. I have that tire size and a there is about a 1 to 2 MPH difference between Speedo and GPS at 70mph.

Tire compounds are like girlfriends. And try to say that any one of them are better based only on size!

Tire compound grip is more based on other factors in the rubber and tread. Yes, there's going to be a slightly larger contact patch, but 10mm extra width isn't going to have a significant difference either way. I doubt one could even get much different in track times with that change. Might be good for 1/10 of a second at best

that’s not bad honestly, and seems like something i could deal with😂

i like that analogy:bellyroll:

thanks for the helpful info! everyone on this forum seems so nice :)

With a new set of Continental ExtremeContact 225/45-R17s my speedometer was right on the money (speedo gets more optimistic as tires wear). Manufacturers almost always calibrate speedometers to be 1-2 mph optimistic at 60mph to make sure they aren't responsible for you go over the speed limit.

On 7" wheels the 225 may be slightly pinched and as a result be a wee bit squishier on turn in. It may also ride a little smoother.

If it’s just for DD, keep stock size for light weight and playfulness.