Mixing same size winter tires

[Naudii_s4]

So I am in need of winter tires and I found 2 Blizzak LM60 225/40/19 and 2 Blizzak LM25 225/40/19. They are the same size and same brand, just different models. I am wondering if it would be bad to put both LM60’s on the front and both LM25’s on the back, or vice versa? The LM25’s have 70% left and the LM60’s were only used for one winter season. Would this mess up anything with the Quattro affiliated on the 2013 Audi S4? Any info will help! Thank you!

[Valpo A7]

Check diameters and circumference of both tires to determine how close they are in size. The numbers match but that does not mean they are exactly the same size.

If you had 4 tires of all the same type and size and 2 of them were warn more than the other 2 then you will have a slight strain on the quattro system. The 2 warn down tires will have more revolutions per mile.

Example from Tirerack:

As an example of different tire diameters resulting from tires worn to different tread depths, we'll compare two 225/45R17-sized tires, a new tire with its original tread depth of 10/32-inch and a second tire worn to 8/32-inch of remaining tread depth. The new 225/45R17-sized tire has a calculated diameter of 24.97", a circumference of 78.44" and will roll 835 times each mile. The same tire worn to 8/32-inch of remaining tread depth is calculated to be 1/8" shorter with a diameter of 24.84", have a circumference of 78.04" and will roll 839 times per mile. While the difference of 1/8" in overall diameter doesn't seem excessive, the resulting 4 revolutions per mile difference can place a continuous strain on the tires and vehicle's driveline. Obviously, the greater the difference in the tires' circumferences, the greater the resulting strain.

[Naudii_s4]

Check diameters and circumference of both tires to determine how close they are in size. The numbers match but that does not mean they are exactly the same size.

If you had 4 tires of all the same type and size and 2 of them were warn more than the other 2 then you will have a slight strain on the quattro system. The 2 warn down tires will have more revolutions per mile.

Example from Tirerack:

As an example of different tire diameters resulting from tires worn to different tread depths, we'll compare two 225/45R17-sized tires, a new tire with its original tread depth of 10/32-inch and a second tire worn to 8/32-inch of remaining tread depth. The new 225/45R17-sized tire has a calculated diameter of 24.97", a circumference of 78.44" and will roll 835 times each mile. The same tire worn to 8/32-inch of remaining tread depth is calculated to be 1/8" shorter with a diameter of 24.84", have a circumference of 78.04" and will roll 839 times per mile. While the difference of 1/8" in overall diameter doesn't seem excessive, the resulting 4 revolutions per mile difference can place a continuous strain on the tires and vehicle's driveline. Obviously, the greater the difference in the tires' circumferences, the greater the resulting strain.

This was very helpful, thank you very much!

[Valpo A7]

I just don't know how much difference is too much. Remember that when you are turning that all 4 tires will have different wheel speeds that are compensated for though the differentials.

My last car was FWD American car and I had to replace 1 tire at some point in its life so I had 2 wheels on the same axle and sometimes on the drive axle depending on tire rotation and I never had any problems out of transmission. I would guess it was 40 - 50,000 miles that I drove it that way. The car had 190K on it when I traded it in on my Audi. Had a Jeep Grand Cherokee 4WD part time that I had 2 new and 2 older tires on it for part of its life and never had any issues in or out of 4WD on it.

The systems are designed with the chance that people will mix tire diameters by accident or circumstances or purpose and will take it in stride with very little if any problems from it.

[Naudii_s4]

I just don't know how much difference is too much. Remember that when you are turning that all 4 tires will have different wheel speeds that are compensated for though the differentials.

My last car was FWD American car and I had to replace 1 tire at some point in its life so I had 2 wheels on the same axle and sometimes on the drive axle depending on tire rotation and I never had any problems out of transmission. I would guess it was 40 - 50,000 miles that I drove it that way. The car had 190K on it when I traded it in on my Audi. Had a Jeep Grand Cherokee 4WD part time that I had 2 new and 2 older tires on it for part of its life and never had any issues in or out of 4WD on it.

The systems are designed with the chance that people will mix tire diameters by accident or circumstances or purpose and will take it in stride with very little if any problems from it.

It’s nice to have some input from someone who has a little experience with this. Thank you! Very helpful

[Naudii_s4]

Update* one pair is at 8.5/32 and the other pair is at 9.5/32. Would it still be a problem to run them together?

[Valpo A7]

Run em.

With only 1/32 diff between them they are fine. Depending on if you do or don't rotate tires you can have that amount of tread diff with just normal wear on a set of 4 that started out life on a car at the same time.

[Naudii_s4]

Run em.

With only 1/32 diff between them they are fine. Depending on if you do or don't rotate tires you can have that amount of tread diff with just normal wear on a set of 4 that started out life on a car at the same time.

Even since they are two different models? You still think it would be okay to do so?

[Valpo A7]

Since they are not matched you might have 1 set that is more aggressive than the other but size wise they will be fine. I was looking up those tires to check dimensions by those sizes and models and found that they may be discontinued which means they are older tires. Some tire companies will not mount tires past a certain age and you will need to talk to your tire jockies about this.

If you look at the back side of the tire you will see a date code near the bead that will tell you when the tire was manufactured.

tire dates.JPG