safe tires for vehicle

[kickingfrog]

Getting a new suv.

 

The old one has winter tires size 17/225/60.

 

The new one is 17/245/60.

 

Is that 20mm narrower for winter tires within the safe zone?

[Jer]

The profile of the tire will also be 12mm smaller, or 24mm (almost an inch) less in total diameter.

 

I imagine that would through your speedo and odometer off a bit.

[whiskywizard]

You would have no trouble mounting the slightly narrower 225s on the new SUV's rims. But as jer said, the different rolling diameter will result in speedometer error; it will be just over 3% off.

 

Even more important than the speedo error is the affect on brakes. 3% is the rough limit on this change or you really affect your ABS. You'd be just over that 3% limit.

 

Have you considered selling the old snows and using the cash to help pay for new ones? Winter tires perform far better in snow if you go to a Minus 1 or Minus 2 configuration. In other words, a narrower, taller tire on a smaller rim. If done properly you will have the exact same rolling diameter but a tire that cuts through snow better.

 

 

 

.

Edited May 18, 2012 by whiskywizard

[Raf]

a narrow tire is generally better in snow

 

you just need a little more sidewall in those 225/60/17s, like Jer said they will be a 'shorter' tire.. you'd propably want a 70 series tire to get the same diameter.

[DanD]

There’s also a small chance that the smaller diameter tire will affect the ABS & traction control. The controller monitors wheel rpm and is calibrated to your vehicle; knowing that the original wheels cannot accelerate or decelerate past a certain point without locking or spinning.

If this threshold is passed you may experience false activation of the system.

Being that there’s only one size difference you may not notice this; but there is a possibility.

 

Dan.

[ecmilley]

3% or less variation is acceptable but the big one is he load rating if the 226/60r17 load rating is lower than the the 245.60r then the tire is unacceptable for use on your suv.

your variation is 3.4% get some new snows

[kickingfrog]

The tires are:

 

P245/60R17

P225/60R17

 

To me that means the diameter is the same. The profile is the same. The only difference is the 20mm in tire width. Do I have this wrong?

 

The tires and rims have only been used for one winter and I would be farther ahead by keeping them, rather then selling them and buying another set in the fall.

 

I know winter tires can be slightly narrower, I just was wondering if 20mm on a 245mm tire was too much or not.

[Billy Bob]

The tires are:

 

P245/60R17

P225/60R17

 

To me that means the diameter is the same. The profile is the same. The only difference is the 20mm in tire width. Do I have this wrong?

 

The tires and rims have only been used for one winter and I would be farther ahead by keeping them, rather then selling them and buying another set in the fall.

 

I know winter tires can be slightly narrower, I just was wondering if 20mm on a 245mm tire was too much or not.

 

I see no problem at all......as a matter of fact more pounds per square inch results in better traction in the snow.....and yes you are correct......they are only slight narrower.......if you were pushing your carrying capacity with the 245's then I wouldn't do the 225's....but I highly doubt you are.

Edited May 18, 2012 by Billy Bob

[Raf]

Do I have this wrong?

 

 

yes you do, if i recall correctly the "60" is the aspect ratio -- not the sidewall height.

 

plug in the two tires sizes and you'll see the 3.4% difference.

 

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

 

Specification Sidewall Radius Diameter Circumference Revs/Mile Difference

225/60-17 5.3in 13.8in 27.6in 86.8in 730 0.0%

245/60-17 5.8in 14.3in 28.6in 89.8in 706 3.4%

 

you are going from a 28.6" tire to a 27.6" tire. May or may not be a big deal, guys in jeeps runs oversized tires quite often (ie they go the other way) but I would listen to the mechanic (ecmilley)

Edited May 18, 2012 by Raf

[kickingfrog]

Right, it is a ratio not a measurement.