Is it safe to run new tires only in the back?
 

I got a puncture in one of my rear tires and really don't want to spend huge money to replace all 4 tires at the moment. Is it a safe to run newer tires on the rear only and keep my used oem tires in front (about 60-70% worn)? I know with AWD cars with a rear and front diff, you want your tire diameters to be relatively the same, but since we are RWD, will I be hurting anything?

Yes. It is recommended to put new tires on the rear.
You'll hurt nothing.

The only reason why you'll want new tires on the back is so you won't oversteer.

I can't recall if it says that in your manual.

Same tires (and wear) on axle - due LSD diff on it (also reason, why in case of punctured rear it's advised to put in back front tires but spacesaver spare - in front. Not an option for those who installed staggered sized wheels/tires). I guess rears wear faster for DD only car. Imho less so on tracked car. Still, one can always rotate tires to even out wear over time, so that whole set arrives to replacement at same time.
@ItsReiko: Repairing punctured tire was not an option due structural damage of carcass or due stock tire repair gunk used? If later .. suggest to "upgrade"/replace tire repair kit with normal spacesaver wheel. It's usually cheaper (vs purchase of two new) repair (if it's repairable) punctured one, and wear will stay same.

no, not a good idea. there's a number of threads from others here that did exactly as you want to do, and immediately have problems with the traction control system flipping out at speed, thinking that the 2 ends of the car are traveling at different speeds due to the difference in tire diameter.

if they're that close, get all 4 tires, save yourself the hassle.

Can you please link to some of those threads? I thought since it's RWD, the rear tires are independent of the front tires?

soundman98: even of same sized same tires just of different wear enough to trigger nannies? :/

I haven't found that yet, I go through 3x amount of rears compared to fronts.
:)

(I also put the new tyres on the front, and transfer fronts to back, as I feel steering tyres suffering a failure is worse than rear suffering failure)

What he said ^ except I personally go through my fronts first. My fronts always wear out faster (track car) and I throw them in the back once theyre basically bald.

Shouldn't be an issue at all!
Our shop car usually eats through its rear tires before the fronts and is frequently drifted on mis-matched wheels/tires. While altering sizes (diameter) front to rear can cause issues, the minute gain in ride height due to fresh tread shouldn't upset the car.

- WORKS Team

It's fine and a common occurance and no, they wont affect the nannies provided they're the same size.

i had to do this earlier this year..one of my michelin primacys got an unpluggable/unpatchable hole and discount tire did not have one in stock not to mention they aren't the cheapest tires so I replaced the rears with 2 new continentals. aside from the tire itself feeling different, i've never ran into any traction issues or weird nanny problems and I just got back from a 300 mile canyon carving trip with lots of slidin around but then again I almost always drive with the t/c button held down mode so maybe that could be a factor..

https://www.ft86club.com/forums/showthread.php?t=78563
https://www.ft86club.com/forums/showthread.php?t=129010
https://www.ft86club.com/forums/showthread.php?t=102531
https://www.ft86club.com/forums/showthread.php?t=99055
https://www.ft86club.com/forums/showthread.php?t=134785
https://www.ft86club.com/forums/showthread.php?t=14677
https://www.ft86club.com/forums/showthread.php?t=141073

that's all of the one's i can find right now.

you're right though, technically, it doesn't matter to the driveline. what is needy in this instance is the wheel speed sensors, and the computer algorithm that drives the traction control and ABS systems. if it see's the fronts moving at a different rate than the rears, it assumes that the car is in a scenario it's not, and attempts to correct the scenario as it's programmed to do.

If you can avoid it, don't mismatch tire compounds front-to-rear.

From personal experience, what @soundman98 says is true. Yes you can drive the car, but the TCS system is going to be very active and the general confidence of the car is going to suffer.

I had a puncture in one of my tires and was running mismatched compounds for a while until I had a chance to replace the tire. I used Hankook Ventus V12 Evo2 and Federal 595 RS-RR, both same size (245/40R17) but paired on different axles. The TCS was way touchier than it should be, and triggering a lot when it didn't used to. The car overall felt more "floaty" and vauge on corners as well.

It is always best to match tires, simple as that. Anything else is a compromise. That said, people do it for cost and for DD it does not likely have as big an issue if just driving around town at normal speeds. If you start pushing it, the negatives will start to show up.

I got a cut in a sidewalk after 10k on my winter setup. I replaced one tire, so it has 10k less then the others. So three BFG comp2 a/s currently have about 52k on them, the other one has 42k. Since I do a lot of highway miles, I have at least another season left. But no issues with the 10k difference so far, but I push these tires less then my summers.