2005 Impreza- tire question

[Stevo F]

Since two of the rims were bent, I recently bought another set of rims (Legacy GT) snowflakes with bad tires.

Plan A is have the 4 Sumitomo tires taken off the existing rims and mounted on the new ones for around $100. The tires have only about 4K miles on them, but from what I've read I'll be lucky to get 30K miles out of them. Actually they are measuring an even 8/32"' of tread (which is rather shocking since I believe they had 10/32" when new, 4K miles ago).

Plan B is to reuse 4 other tires- 3 Mastercraft's that were on my '98 Legacy and one General Altimax RT43 that used to reside on my previous 2005 Impreza (all same size). All tires measure between 7/32" and 8/32" of tread and they all have between 15- 20K miles on them which means they are all wearing a lot better than the Sumitomo's. Since they don't need to dismount a total of 8 tires, the tire place will charge $80 for mounting and balancing these.

In addition I need a 16" spare for my Legacy wagon so I need a decent tire mounted on one of the old Impreza rims for that, so with Plan A, that's an additional $20. I would like have two more iull size spares for other cars, but not a need at this point. Plan B would provide the extra already mounted tires as spares.

I'm not sure what risks to the center differential Plan B would cause on a well used 256K mile car (which incidentally came to me with 4 well worn tires from 3 different sets, but surprisingly not one sign of torque bind). The car is an automatic, BTW.

 

[GeneralDisorder]

Don't mix brands and models of tires. They can vary dramatically in diameter regardless of tread wear and size ratings. 

GD

 

[idosubaru]

GD is right for General one size fits all recommendations. That’s best practice. 

Keep the newer ones - newer is better for winter and rain traction.

That being said I do it all the time.  If you care at all about snow or rain traction use the newest tires that haven’t sat outside I mounted on a vehicle exposed to the sun.  Age and sunlight destroy the material compounds and degrade snow traction like flash paper. 

Don’t go by when you bought them or how old you think they are - There’s a 4 digit date stamp on the sides of tires that tell when they were manufactured. Go by that. 

That aside - these older Subaru’s wear quicker on the front tires.  Measure disasters (or tread depth if they’re all the same model tire) and install the two largest circumference tires up front and they’ll wear down to match the rears. No big deal. 
 

if you’re worried about it run the two larger ones up front in FWD, rotate the front two tires to wear down via the driven wheel if needed and they’ll wear down right to the rear diameters and no worries about it. That’s just a waste of time for me though but if you’re worried it’s an easy remedy. 

Edited August 10, 2020 by idosubaru

[Stevo F]

I'm not concerned with age really (the Sumitomo set is a couple of years newer than the other tires). Main concern is what is the likelihood I'll have issues down the road with the mixed set. Even Subaru's I have with matched sets of tires still have up to 1/32" difference between them (possibly lack of rotating or other factors). These tires have no more than that difference between each other.

I'm also concerned because there is a definite shimmy with the wheels I bought and the crummy tires on them now- it's a lot worse than any vibration I had with the old rims . I really hope it's just the tires and not the new rims. I feel like the old rims currently with the Sumitomo's mounted on them would be a failsafe if the new rims are bent and I don't find out until I've paid to have the Sumitomo's mounted on them and it's my only set of wheels and tires and still may have the same shimmy as the new wheels do now. If I have the other tires put on mmy new rims, I'd still have 2 sets of wheels/ tires to use

[1 Lucky Texan]

you can also run one matched pair on opposite corners, and a different matched pair on the other corners. (unless the Impreza has LSD rear diff)

[Stevo F]

Unfortunately it's 3 tires + 1 tire (no LSD on this car though)

[idosubaru]

You’re sort of juggling a few issues at once it seems - mixing tires, cost, and a shimmy.  I understand that. 

As far as mixing tires I gave you what you need to know to do whatever you want. It’s not a big deal at all if you just pay a little bit of attention. There’s nothing to worry about, don’t let online doomsday preppers dissuade you.  The general commentary about it is wise for the non mechanically inclined masses, but otherwise It’s practically irrelevant for those who dont mind paying attention and can follow logic.