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225/60/15 tires...affect speedo/odometer??

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Old Jun 13, 2004 | 09:33 PM
  #1  
squirrelybird's Avatar
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From: Lutz, FL USA
225/60/15 tires...affect speedo/odometer??

oh man, rainy season is here...i need new tires!

i have the stock 15" x 7" wheels....my last set of tires were 215-65-15 (stock size). However, i think i would rather spend my money on something a little wider. i'm thinking a lot of you run 225-60-15.

what, if anything, will that affect? is the tire height difference enough to change the calibration of the speedometer? the odometer? anybody know?

and those that have gone from small to the above mentioned size, are you still happy with the decision?

thanks
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Old Jun 13, 2004 | 09:39 PM
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From: NWOhioToledoArea
Car: 86-FireBird
Engine: -MPFI
Transmission: T5
Axle/Gears: 3:42
use this

http://www.miata.net/garage/tirecalc.html

you can compare sizes and get a mph off reading.
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Old Jun 13, 2004 | 10:26 PM
  #3  
TechSmurf's Avatar
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From: Tucson, AZ, USA
Car: '99 Trans Am, '86 Camaro
Engine: LS1, Scrap
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Axle/Gears: 3.42 Stock ZT, 3.42 Open
go for 235/60R15, closer to stock diameter (225/60 is actually a hair too small)
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Old Jun 14, 2004 | 04:20 PM
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TomP's Avatar
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From: Central NJ, USA
Car: 1986 Firebird
Engine: 2.8 V6
Transmission: 700R4
P225/60r15

225 = section width
60 = aspect ratio
15 = rim size

1. Divide section width by 25 to get rough "inches" measurement.

ex: 225 / 25 = 9 inches

2. Multiply the result by the aspect ratio, then divide by 100, to get sidewall height

ex: 9 inches * 0.60 / 100 = 5.4 inch sidewall

3. You have two sidewalls, so multiply sidewall * 2, then add in the rim size, to get tire height.

ex: 5.4 * 2 + 15 = 25.8 inch tire height

4. Repeat for the other tire.

ex: Do steps 1 thru 3 for the P215/65r15

If the two sizes match, there's no change to the speedo or "effective rear gear ratio".

If the new tire is shorter than stock, speedo will read faster than normal, and effective gear ratio will be lower.

If new tire is taller, this is the "bad one", your speedo will read slower than normal (could get a speeding ticket) and your effective rear gear ratio will be higher (slower 0-60 and 1/4 mile time).

My front tires are P225/60r15, and the rear tires are P245/60r15.
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Old Jun 14, 2004 | 04:36 PM
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From: Manchester, NH
Car: 91 Firebird
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Transmission: 700r4
When I worked at National Tire and Battery all the tire companies said basically if your going with a wider tire drop the aspect ration by 5. So 215 65 15 stock, 225 60 15 to go wider, 235 55 15 and so on. It's supposed to NOT affect Anti Lock brakes and whatnot.
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Old Jun 14, 2004 | 06:12 PM
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Car: 1992 Camaro RS
Engine: 5.0L TBI
Transmission: 700R4
Axle/Gears: 2.73
Everywhere I have seen that lists two tire sizes for stock 15" Camaro wheels shows:
Stock: 215/65-R15
"Optional": 235/60-R15

Also, according to the calculator link posted by Gumby, going from 215/65 to 225/60 would give a speedometer difference of 1.4% at 60MPH (speedometer would read 59.1MPH) where as 235/60 would give a smaller speedometer difference of 0.4% (speedometer would read 60.2MPH).
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Old Jun 14, 2004 | 06:21 PM
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From: Lutz, FL USA
hmmm...well according to that tire calculator in the link above, the 235/60 would be closer to being the same. the difference is 0.4%, and the 225/60 difference is -1.4%. is 235 too wide for a 7" rim?? would it rub? any other problems?
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Old Jun 14, 2004 | 08:16 PM
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From: Manchester, NH
Car: 91 Firebird
Engine: 191ci 6cyl
Transmission: 700r4
I had a 245 in the rear so it will fit. I think you can go 2 sizes wider on a rim...don't quote me on that one though.
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Old Jun 14, 2004 | 09:02 PM
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From: Tucson, AZ, USA
Car: '99 Trans Am, '86 Camaro
Engine: LS1, Scrap
Transmission: T56, T5
Axle/Gears: 3.42 Stock ZT, 3.42 Open
I run 235/60R15 on my stock 15x7s with absolutely no issues. I haven't seen anyone else running them gripe either.
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Old Jun 14, 2004 | 10:40 PM
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From: Shelby Twp. MI
Car: 91 Z28
Engine: Rebuilt and modified 350
Transmission: rebuilt T-5
Ordered some Yokohama 255/60/15s to fit on my 15 x 7 Cragas street stars. According to Summit, they should fit up to the 15 x 7 wheels.
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Old Jun 15, 2004 | 03:46 AM
  #11  
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From: Wa
Car: 89 RS
Engine: 2.8 (the cruiser)
Transmission: 700R4 (TransGo Kit, VetteServo)
Axle/Gears: 3.42
Originally posted by TechSmurf
I run 235/60R15 on my stock 15x7s with absolutely no issues. I haven't seen anyone else running them gripe either.
Never had rubbing issues of the 235's on my stock rim's. Slight rub problem on a hard steer on the new rims though (They are a little further out).
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Old Jun 17, 2004 | 11:23 PM
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From: surrey b.c. canada
Car: 89 Iroc
Engine: lb9
Transmission: wc t-5
Axle/Gears: 10 bolt 3.08 posi
well my car was 215/60 stock now they have 235/60 will this affect my 0-60 at all?
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Old Jun 23, 2004 | 10:11 PM
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From: Chicago Area
Car: 87 Firebird - Blue - Work in progress
Engine: 305 / 4bbl / No mods - yet.
Transmission: 700R4
Im also running 235/60R15 tires on all four corners with no probs. Glad I did it too as it seem to handle a lot better.
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Old Jun 23, 2004 | 10:57 PM
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From: Hliðskjálf / Pensacola, FL
Car: Camaro
Engine: 3800
Transmission: T5
I thought 23560r15s were big.... weird.

My Camaro has those and I can't cut the wheel too sharp at all or it scrapes like crazy.

Wheels say 15x9 on the inside, wonder if that has anything to do with it. Backspacing is a little different too ... still thought I had bigger tires than stock.

My speedo is way the heck off too (~80=110mph).... I always thought my tire size had something to do with it. T5 swap and 3.23s also factoring in though... aish.

What kinda tire would look good on a 15x9 wheel?

I don't really like the bulge.... but I can live w/ it. Future reference for tires if I dont end up swapping wheels one day...


-Bud
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Old Jun 24, 2004 | 08:22 AM
  #15  
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You got some skinny tires on some REAAAAL wide rims, buddy! I wish I could only have some 15x9's or 16x9's....I'm stuck with 16x7's.

Maybe the scraping is just due to the rims being entirely ENORMOUS and without enough backspacing to clear your fenderwells.....

Not accounting for body clearance...on those rims themselves, I imagine you could find some decent 265's at LEAST.

And to other comments: And as far as running 245 60 15's on a stock 15 x 7 rim.....you CAN do it. The footprint will be a *little* bit off, but they should fit fine. Hell, on some 16x7 rims, you can fit as wide as 255...but the footprint is WAY off then. The tire curls at the edges, making it pointless.
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Old Jun 24, 2004 | 11:47 AM
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on a speedo checker (because of speeding ticket) I figured it was worth a chance. after 35-40 it's like 2-3 MPH off. But that could also just be worn parts.
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Old Jun 25, 2004 | 06:24 PM
  #17  
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From: Johnstown, PA.
Car: Chevy Cobalt & Camaro
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Axle/Gears: Stock 3.23
When I bought my Camaro it had 245/40/15 or 245/50/15 can't remeber witch it was. It was rediculous when I would spin tire the back end would sometimes bounce. Now I have 215/65-15's on all 4. I want something bigger but I don't want to pay 150 bucks a tire.
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Old Jun 25, 2004 | 06:36 PM
  #18  
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From: Palm Bay, Florida, USA
Car: 95 E-150 & 07 Kawasaki ZX-6R
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Originally posted by 87CamaroMan
When I bought my Camaro it had 245/40/15 or 245/50/15 can't remeber witch it was. It was rediculous when I would spin tire the back end would sometimes bounce. Now I have 215/65-15's on all 4. I want something bigger but I don't want to pay 150 bucks a tire.
This is gonna sound like a shameless plug, but I swear it's not! (I work at Tire Kingdom)

I'd recommend the size I ran on my old Camaro....which is 235 60 15. They're not *too* expensive and they perform great.

Tire Kingdom has some wicked deals going on right now...basically, we'll BEAT any other tire store's prices. You bring us any kind of proof that they'll give you a tire for such and such price, and we'll match you with the identical tire, or a tire with similar characteristics (speed rating, XX,000 mile treadlife, etc)....and give it to you for less.

We also exclusively carry the Sigma line of tires...they're a cheaper tire made by Cooper. Most Sigmas are worthless as performance tires...HOWEVER, the Supreme HP and Supreme TR's do pretty well on V6 cars without any insane demand for traction. And they can be had cheaper than most any other performance tire brand. Hey, just food for thought man!

But avoid Sigma Tempests and Shadows like the plague. Regent's aren't much better for performance, although the H-rated Regent Tourings do *ok*.
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Old Jun 25, 2004 | 09:03 PM
  #19  
V6sucker's Avatar
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Car: a car being parted out
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I got a set of 225/50/15 for 62 ea.

I serioulsy recomend the Firehawk SH30. I had them last well over 4 years and 50-60K.

Traction was very good, not real high-po by any means, but very good ALL WEATHER including snow. I did better then some trucks in my neigborhood. Deffiniately did better then the 4 rustangs. I actually helped pull THEM out...
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Old Jun 25, 2004 | 10:08 PM
  #20  
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From: Kingston, Tn
Car: 1987 GTA
Engine: LT1
Transmission: T56
Axle/Gears: 9 bolt 3.70 posi
235/60/15 here and they work just fine, speedo actually is more accurate than with the 215/65's

heh, now you want to see big tires, you should see the 275/40/17's on my Mustang

and believe it or not, they're the same diameter as 225/60's
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