Tires: Replacing one tire on Toyota Tacoma, speedometer accuracy, tire failure

Question
Barry,
I need to replace one tire on my truck. I'm concerned about performance as the remaining tires all have about 6/32 tread remaining. Should I replace two tires instead? In addition, my tires are 235/55-R16 96T. I have available to me at a terrific price 235/70 R16 or 215/55 SR16. I know changing size isn't recommended and that it can affect speedometer accuracy. But, can I safely get away with replacing two rear, or all four tires with either of these other two sizes? All the local guys strongly urge against it - but I think they just want to sell tires. Please advise, and thanks a lot.

Answer
Scott,

The problem with replacing a single tire is that the vehicle will tend to pivot around the odd tire, especially in emergency situations.  Replacing 2 is the standard recommendation - although the absolute best is all 4 - a must if this is a 4X4.

As far as tire sizing goes:  the 215/55R16 is not recommended.  That would be going down in load carrying capacity and that increases the risk of an overloaded tire failure - which sometimes has tragic results.

But the larger P235/70R16? - well, the issue is the amount of space available in the fenderwells.  The folks that measure that sort of thing think the information gives them a competitive advantage, so they don’t share.

I suggest you contact Discount Tire or Tire Rack.  They both do those sorts of measurements.