Tire size
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Tire size
I have a 2007 civic si coupe with stock rims, just wanted to know what tire size is best, google suggests the 87w but the tires on it now are 91w, just want to make sure what i order fits, thanks.
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Re: Tire size
Those are load indexes and speed ratings, not tire sizes. Higher the number, the more weight they can bear. An 87 load index says the tire can bear 1201lbs, 91 is 1356
W speed rating means it can handle up to 168MPH. Higher the letter, the faster it can handle. H rating is probably the minimum I'd go (H rating is 130mph). The faster speed it's able to handle, the stiffer the sidewall is gonna be. Just food for though.
(source)
The numbers you wanna look at regards to tire size are the ones with this format 215/45-17 or 215/45R17
215: tire tread width (width of the tire in millimeters)
45: sidewall height as a percentage of treadwidth (45% of 215 = 96.75mm sidewall height)
17: rim diameter. That wheel fits on 17" rims.
The R just denotes radial construction. You don't really have to pay much attention to that, if at all.
I chose that tire size for a reason. It's the OEM tire size of a 2007 civic si. If you're sticking with stock rims, stick with stock tire size. Now, if you were going to go with 18s or 19s, yeah, you'll need to figure out what comparable overall diameter you'd need. When you change things like treadwidth, sidewall aspect ratio, rim diameter, they all have a potential for messing with speedometer and odometer readings. You wanna try and keep the error as close to zero as possible.
wheel-size.com is the calculator I use to compare tire sizes since it gives you an analysis of how much it'll change, well, just about anything changing tire sizes can change: handling, clearances, scrub radius, speedometer, etc. Put in your OEM wheel/tire size (215/45-17 tires, 17x7 et45 rims), and plug in what you're thinking about putting on to see what it'd change.
W speed rating means it can handle up to 168MPH. Higher the letter, the faster it can handle. H rating is probably the minimum I'd go (H rating is 130mph). The faster speed it's able to handle, the stiffer the sidewall is gonna be. Just food for though.
(source)
The numbers you wanna look at regards to tire size are the ones with this format 215/45-17 or 215/45R17
215: tire tread width (width of the tire in millimeters)
45: sidewall height as a percentage of treadwidth (45% of 215 = 96.75mm sidewall height)
17: rim diameter. That wheel fits on 17" rims.
The R just denotes radial construction. You don't really have to pay much attention to that, if at all.
I chose that tire size for a reason. It's the OEM tire size of a 2007 civic si. If you're sticking with stock rims, stick with stock tire size. Now, if you were going to go with 18s or 19s, yeah, you'll need to figure out what comparable overall diameter you'd need. When you change things like treadwidth, sidewall aspect ratio, rim diameter, they all have a potential for messing with speedometer and odometer readings. You wanna try and keep the error as close to zero as possible.
wheel-size.com is the calculator I use to compare tire sizes since it gives you an analysis of how much it'll change, well, just about anything changing tire sizes can change: handling, clearances, scrub radius, speedometer, etc. Put in your OEM wheel/tire size (215/45-17 tires, 17x7 et45 rims), and plug in what you're thinking about putting on to see what it'd change.
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