The speedometer in my car is off by almost 5 MPH and I'm wondering if it's caused by the wrong size tires on the car.

The owner's manual does not say the tire size and the door jamb sticker is illegible.

I'd live 5 MPH difference except that I need new tires and want to be sure to get the correct size as long as I'm at it.

Thanks.

205/70/15 on LeSabre

205/70/15 on LeSabre

I purchased my '95 new and it came with 215x70x15" tires.
What size tires do you have now and is the speedometer slow or fast?
If they are larger, then original the speed would show a slower mph. If smaller the mph would be faster. Hope I don't have this backwards, ha.

Both of my 93 & 94 LeSabre Limited, were purchased new and came with 205/70/15. Also, 205 is the recommended size for all 92-96 LeSabre cars. An optional size was offered in the 96 or 97 with 16" wheels.
Sizes To Fit Your Vehicle (http://www.tirerack.com/tires/SelectTireSize.jsp?autoMake=Buick&autoModel=Lesabre&autoYear=1994&autoModClar=)
Sizes To Fit Your Vehicle (http://www.tirerack.com/tires/SelectTireSize.jsp?autoMake=Buick&autoModel=Lesabre&autoYear=1995&autoModClar=)

The RPO Code should also tell your size. This is the RPO code for 215/70/15 on my PA: "QPN" - (TIRE ALL, P215/70R15/N WS2 R/PE ST TL ALS 97S)The RPO code should be on your spare tire cover and the tire size code will be similar to the "QPN" code. At least, it should start with a "Q".

Find the code, & post back and I will give you the factory installed size.

Just found out that my 93 Lesabre Limited has RPO code QPE per the spare tire cover label. According to a web site I found, this is the code for 16 inch tires. That's what's on the car now.

Bssed on what I read here with every one having 15 inch OE tires, I thought that mine might have been upgraded from 15 to 16 inch somewhere along the way.

http://www.montecarloss.com/SSThunder/gmcodes.html

Tom

I am running 215s instead of 205s on a 97 with 15 inch rims. I believe the slightly taller 215 (taller sidewall) will cause the speedometer to read about 3% slower miles per hour than you are actually traveling. So if the speedometer says you are going 70 mph, you are actually going about 72 mph or slightly over. If the speedometer says 75, you are actually going about 77.25 mph. It's enough to get you pulled over if you are not aware of it.