Tire Sizing-once more, in detail...

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Jul 23, 2003 | 11:10 PM

jamester

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Tire Sizing-once more, in detail...

OK, I know this has been covered before, Ive read 'em, but...

What's the deal with upsizing the TIRES on a car?

I am trying to swing a wrx wagon, but if not I am going to get the TS and have fun customizing. The one thing I hate about the TS are the crappy 15's on tiny tires that just don't seem right, compared to the wrx/obs/rs. Is it a big deal to replace with 205/55-16's?
I did the "calculator" link, and I think it was saying there would be a 2% MPH difference. I am really most concerned with the speedo, since the fit shouldn't be an issue.

right????

Thanks in advance, I hope to get my first scoob next month!

Jul 24, 2003 | 06:17 AM

Dexter@tirerack

Registered User

Joined: Mar 2003

Posts: 681

From: Warsaw, Indiana

Car Info: 02 WRX Wagon White

The TS and the WRX wagons use different tire sizing - the TS tires are generally about 1/2" shorter on average, and speedometer calibration will reflect this. On the 15x6 wheel that comes with the TS, you will be confined to the original tire size 195/60-15, which has an outer diameter of about 24.2". If you get a set of 16" WRX wheels, the recommended tire size on the TS is 205/50-16 - which is about 7/10" shorter than the 205/55-16 that the WRX uses. The taller WRX tires would fit fine, but then you run into the speedo error - which in this case is small but must be considered. You will be going almost 65mph when your speedo says 63.

Jul 24, 2003 | 09:08 AM

XstephenX

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You will also put more mileage on the car. Not that a 2% diff would matter much

Jul 24, 2003 | 09:22 AM

Dexter@tirerack

Registered User

Joined: Mar 2003

Posts: 681

From: Warsaw, Indiana

Car Info: 02 WRX Wagon White

Bigger outer diameter = less mileage, because of fewer revolutions per unit of length traveled. XstephenX knows this, he's just testing me.

Jul 24, 2003 | 10:28 AM

jamester

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So, if there is a 1/2" difference in diameter with both tires stock, and the plus-sized 16's have a 7/10" difference, then that means tire size DOES increase along with rim size (and width)? But not AS much as going up to the wrx size, so the speedo is not affected?

Do I have this right? And if so, then plus sizing the 15's to 16 will give me a bigger, better looking tire/wheel combo?

thanks again, just trying to really get this down....

Jul 24, 2003 | 10:57 AM

Dexter@tirerack

Registered User

Joined: Mar 2003

Posts: 681

From: Warsaw, Indiana

Car Info: 02 WRX Wagon White

If you follow the recommended plus 1 (increase 1" in rim diameter, preserve outer diameter) then the diameter doesn't change noticeably .1" or so. This is with the 205/50-16. If you put WRX wheels and WRX sized tires (205/55-16)on the TS, the diameter increases by about 7/10".