I'm trying to find a decent way to lower rpm at highway speeds. My wife would also like a little softer ride than the 205/40/17s are supplying. I'm thinking either 215/45 or 225/45, but don't know if 225s would be too tall, too heavy, or hurt mileage or performance. I'll definitely be adding spacers of at least 15 mm in back. 205/40 to 225/45 would be an increase of 1.6" total height, from 23.4" to 25" (Kumho 711). Wheels have +37mm offset. Thx.

 

I run 215/45/17 with a 2" drop and It rides really nice, not too much different than stock. I don't know if you can go any bigger without rubbing.

 

225 would be the tread width... not how tall it is...

if you are worried about a smoother ride, go to 16's or even 15's

 

The width matters because the side wall is a function of the tire width.
I have 225 40 18 and it rides very nicely. I have Kumho 711 which are not high performance tires ( but neither is the car) and they ride super quietly.
My wheel/tire combo is about 1" taller and it does lower the RPM at highway speeds.
How much" I don't know exactly, but a guestimate would be around 200 RPM less at about 70 MPh

 

i think he's compairing 215/45 to 225/45, and yes it will still be taller than 215/45(0.2 inch difference).

 

btw, if you're going with it, let us know how it goes. what is your wheel specs(width, offset) and is the box lowered?
I want to go that way on my next rubber(2-3 years later)
I have 215/45/17 on 7" et 38 lowered s-tech(1.7, 1.5) and no rubbing. rides is not bad at all.

 

oh and one other thing . 205/40/17 is small , 205/45/17 is a better choice. but yeah the bigger the tire , the slower yer car is and the worse mpg u get so..... a heavier , taller tire may lower rpms but u will still be getting ____ty gas mileage from the added unsprung weight. try some 15 or 16s with tall tires , try like a 195 or 205/60 15

 

Sid, I have 17x7" +37, stock ride height. No new springs planned, so that won't be an issue. I'm more concerned about the added weight of wider tires.

Looks like 215/45 may be the way to go. Thanks guys.

 

Be careful bro, running a bigger tire will help your ride, but trying to get the RPM's down will change the accuaccy of your speedo.
Over all dia of a stock tire is about 25.39"
The 215/45/17 is 24.6"

My 225/35/20 is 26.2, and it throws my speedo off around 5-8 MPH... I think.

Just letting you know, BTW I got most of my info off Nitto's website. I did the math for
the stock tire myself.

Good luck!

 

Yeah, I know there will be a little change in speedo readings, but my wife hardly ever approaches the "ticket" range any way. Thanks for the input. Now I'm debating 225/45s or 215/45s.