Winter Tires and Odometer

[jaynine89]

Hey, all,

With winter just about here, I've been looking into winter tires for my truck. Right now I have 15" 225s, and I'm wondering if changing to 215s would affect my odometer or speedometer. My coworker has some 215s with 75% tread I may buy. To be honest, I'm not entirely sure what all of the numbers on the sidewall of a tire mean, so if there is an affect, I'd have no idea.

Thanks.
jaynine89

 

[wildbill23c]

I know I had 235's on my 84 B2 when I first got it, and I recently got new tires on it and put 215's on it with the 235's my speedometer was off about 5mph, now its almost exact, probably if I went to 205's it would be exact. However, in your case you may not notice too much of a difference. If your speedometer is correct now, and you go down a size, your speedometer may only be off 2-3mph so when your speedometer says 55 you'll only really be going about 53mph or somewhere around there.

 

[jaynine89]

Alright, thanks for the pointers. How do you find out what the OEM tires are? I assume those are what the odometer/speedometer was calibrated to...

 

[YungICY]

I'm not sure but the OEM tire size might be on the door sticker.


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[martin]

There's a link somewhere on the site that explains the numbers on the tyres, however, you need to know all the numbers to be able to give a reasonable answer, the profile (middle number) is important and might be anywhere from 30 to 80, it affects the outside diameter of the tyre.

 

[kunar]

There's a link somewhere on the site that explains the numbers on the tyres, however, you need to know all the numbers to be able to give a reasonable answer, the profile (middle number) is important and might be anywhere from 30 to 80, it affects the outside diameter of the tyre.

this. the first number is only the width of the tread and will have no effect on the over all diameter alone. the second number is the aspect ratio, in other words the height of the sidewall in relation to the tread width. so a 235-75-15 is 235mm wide at the tread block and 176mm (235x0.75) tall sidewall. if the tread width increases, the aspect ratio must decrease to keep the diameter the same. find the rest of the information for both sizes of tires and get back to us.

 

[wildbill23c]

The OEM size would be on the sticker on your driver's side door or around that area, sometimes it is on the door, sometimes its stuck on the actual door frame by the latch on the cab.

 

[alwaysFlOoReD]

On some vehicles another place to look for tire info is the glovebox door.
I don't think there will be a significant change but you can check with the calculators on this page;
http://www.therangerstation.com/tech_library/index-wheels.shtml
Good luck,

Richard

 

[jaynine89]

Alrighty

I ran outside to check out what I'm running right now, and I have 4 Kumho Solus KR21s all around. They are P225/70 R15 100T tires, M+S with DOT numbers H282 YR6V 2710.

The door says P225/70R 15 SL, so it seems I'm running the correct tires on 15x6.0J rims.

 

[frdtrknut]

Another resource can be the tire manufacturers website. You can go there and look up your tire and often there is a specification section that gives you lots of info.

Added note: Even with tires with like numbers it is best to use a tape and measure the circumference, especially if you have different brands on the same 4x4.