Need new tires.???

[6500rpm]

I wouldn't mismatch, it's the diameter not the width. I went with 255's all the way around and couldn't be happier.

 

[Sgtmeatsauce1]

I don't understand, 255/45/20 is not significantly different, then 245/45/20....not like if I did 255/40 or 255/50 vs 245/45.....what is likely to happen? I would get the other two in like 4 months or 6000 miles during what would be rotation time.

 

[Sholab1]

I don't understand, 255/45/20 is not significantly different, then 245/45/20....not like if I did 255/40 or 255/50 vs 245/45.....what is likely to happen? I would get the other two in like 4 months or 6000 miles during what would be rotation time.

255/40 is. .65 inch (16.5mm) smaller than 45, 2.3% smaller than 245/45

255/50 is 1 inch (25.5mm) bigger than the 45, 3.3% bigger than 245/45

255/45 is. .35 inch (9mm) 1.2% bigger than the 245/45

I always swap the 4 being awd, if it were front or rear wd I would not care as much

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[SHOdded]

I think you'd be ok to do 2 tires at a time, but on the same axle. The AWD system cares more about that than all 4 tires being the exact same tread depth. Of course, you should have the same MODEL of tire (eg continental dws06) on all 4 corners, so that the tread pattern, handling characteristics, etc remain the same. You can fudge it with different models of tire (again, should be the same on an axle) for a short while as long as you do not put the AWD in a tough spot.

 

[6500rpm]

I'm running factory springs-not lowered, and while not a huge difference in diameter, the 255's just seem to help fill the large void between the tire and wheel opening that the SHO exhibits. I'm not well versed on the all wheel drive system on our cars, but any mismatch on my 4wd Montero Sport with limited slip diffs makes the thing pretty much undriveable. I'll have to make some time to poke around the Oasis site and see what's in the rear diff on the car other than the electrically applied RDU portion.

 

[SHOdded]

This is the nice thing about Ford's Intelligent AWD system, it does make allowances for mismatch as long as both tires on an axle are matched. Even if they are mismatched on an axle tread pattern wise but matched (more or less) heightwise, it will still work. Now are you going to make AWD work harder? AdvanceTrac? Yes, stability and control systems are obviously affected by tires with mismatched tread patterns.

http://wardsauto.com/technology/demand-growing-ford-s-intelligent-all-wheel-drive-system
http://www.atraonline.com/gears/2009/2009-09/2009_9_20.pdf

 

[Sgtmeatsauce1]

It would be 2 new tires one size larger, 255/45/20 rather then the stock 245/45/20. It would be two better different brand. Both would be put on the front first. My car came with Crappy made in China Chinese brand Zenna Argus UHP, dealer had them on the car when I bought it. Suppose to have summer tires as my car is a PP car. The tires SUCK, I found them on the net for 87 bucks for a 20 inch tire is Really cheap. I don't do any slinging around corners. Straight and fast for me. Planning on driving from NJ to Naples florida to help fix and clean families properties after the storms. I have 20,000 on these tires they are half way down, rotate every oil change 5 or 6000 miles. Looking at Cooper Zeon AS3, General G Max and BFG sports.....all about same price, all are all seasons. I ran all 3 before. The Zeon were the best tire I ever had, on my 8 sets of tires on my old G8 GT FBO rear wheel drive car. Other two were awesome too, G Max was decent in the snow. The Zeon I could floor in the rain, stop on a dime, would hope they half as good on the SHO and with awd should be remarkable.

 

[limited02]

I believe as long as there is less than a 3% difference in size, you can run what you want. Just keep the two fronts the same and the two rear the same, obviously.

I went with 255/45/20 all around and the ride is so much better.

 

[Johnbigdog]

I like this website. It help me out a lot when going to the 18 inch interceptor rims.

https://tiresize.com/calculator/

There is a difference in height between the 245 and 255 width. Your AWD may not like that much difference between a new tire and used tire. A rule of thumb for 4x4 trucks is .5 inches.

Oh, and the website will also help in determining how much your odometer and speedometer will be off.

Fun fact. If you have navigation and your tires are wrong, you can throw off the navigation. When there is no or poor GPS signal it watches wheel speed and direction.