1999 Tacoma wrong mileage

Hello,

Was hoping to get some insight into a speedo/mileage issue. I bought my Tacoma summer of 2014. Its a 1999 3.4L 4WD. I noticed the odometer and trip meters do not accurately record miles. I first discovered this a while back because I had directions from mapquest printed out and it was roughly a 40 mile drive where I was going. I cannot remember how short the truck was compared to map quest mileage but it was several miles on the low side.

Anyway I got to looking and I knew the truck had 16" wheels on it and I didn't know any better, I thought they came factory with 16s. Well apparently they should be 15s.

Right now it has 16s on it with 265/75-R16 tires. I did some research and from some articles I was reading even the factory 15s with the factory tire size will make the speedo read wrong and the suggestion was to do a different tire size to correct it.

If I went back to 15s does anyone know what size tire to put on to get the speedo accurate? Or are 15s and factory tire size good enough? I filled the truck up with fuel yesterday and calculated out my MPG and it was like 12.69MPG. I am hoping this is more like 15-16 miles per gallon if it was actually reading miles correctly although it is pulling a trailer most of the time with lawn mowers on it.

Any help/insight would be much appreciated.

 

its printed right there on your drivers door pillar sticker

you can also replace the speedo gear in the tranny to correct the mileage readings so you have two options

 

I wasn't even thinking about that sticker, brain fart on my part. Thanks for telling me. I read your post and I was like "DUH!"

 

I'm not sure that you tires/wheels are the problem. I have a 97 (which came stock with 15s and smaller tires) and have upgraded to the same size you have listed (265/75R16). My mileage/speed is pretty close to dead on.... I don't really have any suggestions, but before you go and buy new wheels and tires, you may consider something else in the system that could be causing the problem.

 

good point, if the overall height of the tire is the same then changing rim sizes means nothing so make sure the heights of the tires are different of its not going to matter. if that is the case then your speedo gear might be bad and not sending the right info.

get on the highway and find one of those green mile markers and note your miles, then drive to the next one and see if its exactly 1 mile changed

 

Just for clarification, the 265/75R16 tires are a bigger tire than stock and did affect my odometer/speedometer slightly (around 2-3 mph slower), but actually caused a more accurate reading of distance/speed.

Here's a site that will help you determine what the actual difference should be:
http://tire-size-conversion.com/speedometer-calibration/

Also keep in mind that tire pressure can influence these numbers as well.