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Is Toyota Stupid or is it just me?
Today, i called 3 different dealership service depts, and got 3 different answers.
I have a gen 1xb... when i got it originally, i opted to have the dealer install 19 inch TRD Racing Hearts before i took delivery. My box has never seen stock tires... So one day, i was out on the freeway going on a trip to San Francisco and i decided to check my speed via my handheld GPS unit. Well when i hit 80mph on my spedo, the gps unit said i was doing 79.98mph.. Ok no issue so far right, cus i figure the dealer reprogrammed my ECU to reflect the change in wheel/tire size, keeping my spedo and odo inline with real life..
well, 3 years later i now have new rim and tire combo... 18's (cuz Axis don't make the widetrack in a 19 inch). i went from a 225/35/19 to a 225/35/18. Now when i gps the speed, my spedo is saying i am going faster then i really am, which holds true if the dealer originally reprogrammed my ecu.. the 18's do spin faster then the 19's at the same speed - they make more rotations over a given distance because of the reduced circumfrance., which appears as higher mph on the spedo..
So i checked a few tire size calculators, and sure enough, i get the same % of difference that i see on my gps.. so for $hits and giggles, i check the dif from a stock xb rim/tire combo to a 225/35/18 and a 225/35/19..
if i had gone from a stock rim /tire to a 225/35/18 i should be showing a decrease in mph because the 18's on a 35 series tire are bigger then stock, but low and behold... i am showing that my speed is faster then it actually is... which also means that my odo is racking up miles that have not actually been put on the car..
so today i call 3 dealerships, one tells me that there is absolutely NO WAY to reprogram the ecu, and i have to live with it. Another dealer tells me in his "honest opinion it has never come up before and isn't really that big of a deal, just remember that you are 3% slower then what the speedo says." ok i have failed math since the 8th grade... so um, how about whats 3% of i'm not happy? The third dealership says it can be done, but they send their jobs out to another company.. He gives me the phone #, and guess what, disconnected... i call back to check the numnber and he says "thats the only # we have, sorry" so i ask what will you do when a customer buys a new car, and puts some dubbs on it? and he says, we'll put the 20's on it, and make it the customers problem, if they wanted to keep the speedo correct, they should stay with stock rims / tires.. which i agree with totally, but damn, when we live in an age where i can start my car from 300ft away, where i can watch a japanese girl in japan do freaky stuff in real time on my laptop , where we can order dinner via the internet, where our cars (mostly) have computers comperable to the ones in our gaming systems, why can't a simple corection be written to the program to account for a rim / tire change?
Am i asking for the world? Does anyone out there know how to fix this? i know 80% of us are rolling on larger rims? What do you all do?
I would like to hear from as many as possible.

 

To the best of my knowledge, the factory (Japan) tire size was 185/65/15. When they came to the state, it got changed to a 185/60/15 giving an approximate 3% error. You put on a 225/35/19 which is 6% off from the US stock tire and 3% off from the Japanese tire. Then, you went to a 225/35/19 (your profile says 215/35/19 which is <1%) which is about 2% off.

I can all but guarantee you that the original dealer did not reprogram your ECU. When plus sizing tires, you should always strive to keep the overall height the same to prevent this sort of thing. Most sites even tell you within 3%. If you don't, you get to live with an inaccurate speedo/odometer. That's just how it is. The Chevy set has it easy. There are lots of aftermarket companies that make programmable modules that will interface between the VSS and the speedometer to allow you the adjustment you need. My guess is that since this isn't available for the Scions (or lots of imports) that it isn't quite easy.

Modifying cars is cool. Unfortunately, sometimes when you mod you have to deal with things that don't always work like they would from the factory. This is one of those things. Any idea how far off your speedometer is with stock wheels and tires? How accurate is your GPS? Small errors add up too. Good luck!

 

If the speedo could be programmed I would imagine people would do it to shave their mileage. Like in the old days of turning back the speedo.

 

Im new to the scion life but have lived in the s-10 life for many years. I know that with a s-10 you can get a hypertech power programmer that will allow you to adjust the spedo to accommodate different wheel and tire size and also rear differential gear ratios. I have no idea if they make one for the xb or not but it may give you some direction to look. Only down side to them is that they coast about $350. On the up side of them they can adjust shift points, power curve, spedo, and top end governor, red line, and speed governor.

hope this helps

 

225/35/18's is oversized , so is 225/35/19

and the dealer didn't reprogram anything

 

...I'm still trying to figure out why you assumed the dealer would have re-programmed your speedometer just because you had a non-stock wheel/tire combo installed!

 

yeah.. the dealer didn't reprogram anything..

because they really can't

 

79.98mph and your speedo said 80MPH. Big deal. Did you ever think that your GPS could be off too? Talk to some 4X4 guys about your problem. They would laugh in your face.