[Spencer925]

Hey guys, so I bought new tires (90% tread left) but they're not all the same tread pattern. They're evenly work (came off a forester) though. Would mounting these tires be a bad idea or make a difference at all? Also they're 225 45 17 instead of 225 55 17. Thanks!

 

[eagleeye]

moved thread to tire section.

in the short term, I would put one matching each on the front and the rear. and avoid driving the car. unless your goal is to wear parts out.

tread pattern does matter, not just size. (different size is really bad :surprise.

next. get 4 tires all the same.

sell what you got to 2wd people.

_____

last week I was looking at a 2015 ford escape 2.0T on a lift for exhaust rattles,
owner's son said his senior citizen dad wanted to trade it for a new jeep as the AWD acted funny.
(had 2 snows on the front, and 2 all seasons on the back ....same size written on them anyway,...probably a couple cm off if measured,...and I wondered what fool at the tire shop let the thing out the door without selling 4 snow tires just the same as spec'd right in the owners manual.).

 

[stevenva]

That would be a bad idea.
They are not new tires by the way.
I wish your post title said I'm about to buy a set of mismatched and wrong size used tires for my Subaru. Now that you've done it it's still a bad idea.
You can probably get away with it short term with hopefully little if any harm to your machines inners. I drove mine from Long Island to Virginia with 2 new and 2 old tires when I bought it. Over time at the very least you will cook your ATF.
Unload them for whatever someone offers and put it towards proper tires.
Myself and anyone whos been in Costco or bought something online understands saving money. Tires are an exception. Just 4 little rubber patches on the ground have complete control your cars behavior and safety.

 

[mjohnson]

I got a flat last week (gd roofing nail *shakes fist*) and had to use my spare for the first time. In the 20 clicks (12 miles) I drove it, I could feel the car driving differently coping with the 1 mismatched tire.

As others said, just sell them and buy 4 new ones. We're not pulling your leg, this info (never use mismatched tires) is in the owner's manual.

 

[1 Lucky Texan]

The factory has always suggested 'rolling circumference' between all the tires be within 1/4" of each other. It is 'possible' that different models or makes of tires 'happen' to have the same circumference. But it's very unlikely and , if they wear at different rates, they soon will be out of spec.

The risk of damage is great and it's just better all-around to run the same tires at each corner - safer too as handling, rain performance, braking are more predictable.

 

[dukey33]

I'm gonna paddle upstream on this one.

If the four tires you bought are all the same size, the different tread patterns will have no impact to the AWD system. If you want to be OCD about the sizing, measure the circumference of all four tires to convince yourself they are close to the same.

There *may* be some handling differences between the tires and they may wear at different rates. Keep an eye on them and rotate regularly or sooner if you notice one pair wearing more quickly than the other pair. Keep the pairs on the same axle.

 

[eagleeye]

what happened to the forester they were on?


did the person that was running such a mis-matched set of tires ruin their car?,....or run it into a tree? ...thereby freeing its parts to other subaru owners to pick off of.

I see you got a 2005 XT. ...a rather fragile beast on maint.....and easy to ruin.

 

[idosubaru]

1. no big deal.

2. if you're unsure or don't have a good eye - put the "larger" circumference tires up front - measure them in case the brands have slightly different construction leading to differing circumference.

if tread pattern mattered then every time we get uneven mud or uneven "rock in the treads" distribution or differing CV boot grease/material/weight/articulation/OEM/aftermarket would be bad and we'd see Subaru's litering the sides of the roads with busticated transmissions.

it's not happening.