Tires: Tire upgrade, wheel diameter, transmission work


Question
I have a 94 Honda 2dr automatic and drive 600 miles a week. It has 14" tires and I'm thinking of upgrading to 17" tires. Will the reliability be affected?

Answer
Angelo,

The answer is yes!

If I have this right, your vehicle came with P185/70R14's.  A change to 17" (maintaining the overall diameter so the speedo isn't affected) means you need to use a P205/45R17.  
The lower you go in aspect ratio, the more likely it is that you will experience problems with impact damage - that is tire and wheel damage caused by objects or potholes.  Tires this low just don't have enough sidewall.

This means both your tires and your wheels have an increased probability of being damaged.

A while back, I created a list, based on my experience, to try to address the question of how low you could go.  The list is still in development, but a P205/45R17 is at least 2 sizes from being adequate (IMHO).

But I think the question you were REALLY asking was about the rest of the car - the engine, transmission, suspension, etc.  From that point of view, I think the increased wheel diameter (with its increased weight) is going to have a minor negative affect on the overall car.  

The increased weight is going to make the engine and transmission work a little bit harder.  The increased weight is also going to be harder on the shocks and the springs, not to mention the increased stiffness of the tire negatively affecting the ride quality, making it more likely to rattle something loose or decrease the point at which something cracks.

But these things are relatively minor compared to the impact issue.

Hope this helps.