Flat tire - spare size question

[Anita]

Do you think the new tire paired with one with about 9K miles on it cause a problem?

[Anita]

Okay, so I have a new Kumho 255/55/18 on the left rear. I am noticing a slight whine while coasting - just like the whine I get when i have a low air tire. The kumho definitely has more knobby tread.. my Nitto has the flat street design.

Next question: Do I buy another Kumho and run two new tires in the back with the Nittos on front, or do I buy a Nitto and replace the Kumho (leaving the Kumho as an emergency spare)? If the latter, would the truck react to a new Nitto and a used one on the back?

[uncle_asa]

Next question: Do I buy another Kumho and run two new tires in the back with the Nittos on front, or do I buy a Nitto and replace the Kumho (leaving the Kumho as an emergency spare)? If the latter, would the truck react to a new Nitto and a used one on the back?

It is bad for transmission if you have tires with different threads because of different contact with the road, so it is better to order the one you already have on the rest 3 tires and use different thread as instructed for donut. Otherwise you have a chance to kill your limited-slip differential so it become regular open differential or you might have TOD/ABS to fail in some cases.

[Anita]

Yesterday, I spoke with my mechanic and he thought it was a bad idea to have tires with very different tread patterns on the truck. The differences of "wander", i.e. how the tire tracks can cause unusual wear on the tires and a potential problem in general for the truck. Replacement Nitto should be coming this week and the Kumho will be placed on my spare rim for emergencies. Thanks to all for good advice and a great discussion about spares.

Epilogue: New Nitto was put on and the whining stopped. All is well with the world. Maybe I am super sensitive to sound but its interesting that same size tires with some difference in tread wear and pattern can create enough change in the mechanism to produce unfamiliar sounds.

[Chopper]

Unless they are gumball re050s or you drive really, really hard....no.