OT: Tire Replacement

I have an old FWD Olds with over 350k miles.

I have a bad tire and some other tires on-hand.

Current 4 Tires:  P205/70R15
Newer 2 Tires:   P205/65R15 (slightly shorter)

Is there a problem replacing 2 front or back with the new(er) tires?  Better on front or back?

I'd say spring for the same tires all around. But then I am a former RCMB baller.

SawGreen wrote:I have an old FWD Olds with over 350k miles.

I have a bad tire and some other tires on-hand.

Current 4 Tires:  P205/70R15
Newer 2 Tires:   P205/65R15 (slightly shorter)

Is there a problem replacing 2 front or back with the new(er) tires?  Better on front or back?

I don't know, is there a problem? Do you gotta problem with it? Is there a problem here? Are you sayin' there's a problem or somethin'?  'Cause... to me....you know?.... it kinda sounds like there's a problem here. I dunno. Maybe I'm hearing it wrong.

Well "they" say you should replace the back first to avoid losing traction in water or on slick spots.

But a good honest greasemonkey will tell you that the front always wears out faster so you can usually replace those first without any issues.

Just put two on the front of a car I'm selling to save dough.

SawGreen wrote:I have an old FWD Olds with over 350k miles.

I have a bad tire and some other tires on-hand.

Current 4 Tires:  P205/70R15
Newer 2 Tires:   P205/65R15 (slightly shorter)

Is there a problem replacing 2 front or back with the new(er) tires?  Better on front or back?

My advice is to never use different sized tires than what the manufacturer recommends. Some exceptions to this would be if you are increasing the wheel size (doing a "plus one" or "plus two" meaning you swap your 15" for 16" or 17" wheels, then put lower profile tires on them, keeping the overall tire circumference the same as the 15" wheel/tire combo).

If you change the size of the tire, your speedometer and ECU will not work properly, your odometer will not track mileage properly, you'll get worse gas mileage, your transmission shifting points can be affected, and so on. Using different sized tires on the front than on the back will have potentially negative affects on handling and braking.


Having said that, it's not like your car will not work with smaller tires on one axle than the other. It just won't work as well. If you can live with the speedo not working correctly and some crappy handling characteristics (moreso than a 350k mile FWD Olds already has), the newer tires would be better on the front than on the rear.

Rocinante wrote:Well "they" say you should replace the back first to avoid losing traction in water or on slick spots.  

But a good honest greasemonkey will tell you that the front always wears out faster so you can usually replace those first without any issues.

Just put two on the front of a car I'm selling to save dough.

On a FWD car, the better tires should always be on the front.
The front tires are handing the bulk of the traction for braking, turning and acceleration.

This is less of an issue with RWD cars, but still good practice to have the better tires on the front as braking and turning are usually more critical than acceleration traction.
AWD cars need all four tires to match and usually have specific tread depth tolerances before all four will need to be replaced simultaneously.

Thanks for the replies.  It's a car on which new tires would be worth more than the car itself.  Still, I was curious about the spedo and transmission possibilities.

It probably would have been fine given how this vehicle is used.  But, I was able to go to the local steel yard and get 2 70R's for $15 bucks each (hopefully no ghosts attached).  Got them installed and balanced for another $30.  So $60 and it's back on the road.