Tire question

skozzy · #1 (**permalink**) 10-26-09, 02:42 PM

Just wondering, I found a set of Dunlop Wintersport M3 snow tires for a pretty decent price (used with only 5K miles on them) and I am thinking about getting them to use this winter and take off in the spring. My question is will the work? The size is 225/45/R18. I am concerned with them being 225's. Any ideas? If the won't no big deal but the price is right if the will work.

ChrisHall · #2 (**permalink**) 10-26-09, 03:28 PM

Stock tires on your car are P235/50R17. With these new tires you'll need 18" rims instead of 17". When your speedometer is saying 60mph, you will really be doing 59.4 mph. The diameter of original tires is 26.25" and the new tires are 25.97".

Size isn't everything though. What is the speed rating and weight rating?

Assuming Speed and Weight ratings are good, this tire size is fine for the car.

skozzy · #3 (**permalink**) 10-26-09, 03:31 PM

Quote:

Originally Posted by ChrisHall

Stock tires on your car are P235/50R17. With these new tires you'll need 18" rims instead of 17". When your speedometer is saying 60mph, you will really be doing 59.4 mph. The diameter of original tires is 26.25" and the new tires are 25.97".

Size isn't everything though. What is the speed rating and weight rating?

Assuming Speed and Weight ratings are good, this tire size is fine for the car.

I have the 18' wheels, 1SG AWD

nguyendot · #4 (**permalink**) 10-27-09, 11:14 PM

I would not go skinnier than stock, 235 is already pretty skinny for our big cars. Stick between 235 and 255

ChrisHall · #5 (**permalink**) 10-28-09, 08:42 AM

Quote:

Originally Posted by nguyendot

I would not go skinnier than stock, 235 is already pretty skinny for our big cars. Stick between 235 and 255

This is just your oppinion. Not a fact. Fact is, skinnier tires work better in snow. And since this is what he is talking about, the 225's are perfect.

nguyendot · #6 (**permalink**) 10-28-09, 01:00 PM

Quote:

Originally Posted by ChrisHall

This is just your oppinion. Not a fact. Fact is, skinnier tires work better in snow. And since this is what he is talking about, the 225's are perfect.

So you're saying it's OK to mount a 225 tire on a 255 rim? That's going quite skinny there. That would reduce the load capacity of the car, and it would be 30mm less wide on the rim, which may not create the correct seal.

It's not a matter of working better in snow, it's a matter of keeping the same load capacity. These aren't light cars. Since he'd be getting a skinnier tire, it would have less air in it. To keep the same capacity he would have to increase the height of the tire from the stock 45mm to 50 or 55mm. This would offset his rolling diameter and mess up the speedo.

ChrisHall · #7 (**permalink**) 10-28-09, 01:26 PM

Quote:

Originally Posted by nguyendot

So you're saying it's OK to mount a 225 tire on a 255 rim? That's going quite skinny there. That would reduce the load capacity of the car, and it would be 30mm less wide on the rim, which may not create the correct seal.

It's not a matter of working better in snow, it's a matter of keeping the same load capacity. These aren't light cars. Since he'd be getting a skinnier tire, it would have less air in it. To keep the same capacity he would have to increase the height of the tire from the stock 45mm to 50 or 55mm. This would offset his rolling diameter and mess up the speedo.

Front Tires on this car are P235 45R18. (Diameter of 26.33")
Rear Tires on this car is P255 40R18. (Diameter of 26.03")

He wants to go to P225 45R18 (Diameter of 25.97")

I see a difference in height on fronts as being .36" (.18" at axle)
I see a difference in height on Rears as being .06" (.03" at axle)

The tires he is looking have a load index of 95 (1521 lbs) and a speed rating of V (149 mph). Which is a little low on both, but I never said they were good based on these values. Only the sizes.

nguyendot · #8 (**permalink**) 10-28-09, 07:02 PM

Don't AWD cars have the same wheels/tires on all 4 corners?

EChas3 · #9 (**permalink**) 10-28-09, 10:44 PM

Quote:

Originally Posted by nguyendot

Don't AWD cars have the same wheels/tires on all 4 corners?

Not mine! Same wheels, different tires on the 1SG AWD.

If you're going to buy 18" rims for the snows, I think you'll be very happy. The optional OEM 18" wheels are too wide (IMHO). Why spend a lot for winter wheels anyway?

bierman.d · #10 (**permalink**) 10-29-09, 01:26 AM

Quote:

Originally Posted by nguyendot

Don't AWD cars have the same wheels/tires on all 4 corners?

Oddly enough, not on this car.
Just a way to make things more expensive I guess

235F, 255R.

I have a set of Bridgestone Blizzaks, 255 in the rear, and I think 245 front.. I get around great! Real story is before that though: these same tires came off of a 2003 SVT Mustang that I drove a couple years back. A low, RWD convertible and I never got stuck in the harsh Iowa winter. They perform admirably on dry pavement, too (I have them on now).
Thinner tires are better for snow, but I don't know if you could get away with 225s on this car. I'd look around for at least 235.

ChrisHall · #11 (**permalink**) 10-29-09, 08:18 AM

Where is the speed sensor on these cars? Front or back?

Chris

skozzy · #12 (**permalink**) 10-29-09, 10:54 AM

Thanks for the input guys! I am going to pass on these and just get the 255's, I have 255's on all four corners right now. Guess I am getting ahead of myself anyway. Will be the first winter with this car. Currently I have Vogue all seasons on it. I guess I will see how these do and make my mind up from there.