title edited for new content. looks like I may get the 50 series tires, anyway. Odo error or not. Speedo correction could be gotten by a custom dial face.




First thing: I'm planning to drop 2" on Goldline lowering springs. They are on backorder at present.


Say! When someday I need new tires, can I put a 50 series/same width on the 15" steel wheels? I don't know anything about tire sizes... But if I do this, can the speedo-odo computer be recalibrated for the smaller tire radius?

I like this prospect of one full step down in aspect ratio. I would want to keep the same width.

What are the results? Imagine the revs go up moderately. But that's OK! More torque, better accelleration! Less unsprung weight by a -bit-. Better cornering! Further reduction in C.G. and a bit lower look, again, PLUS regaining a bit of suspension travel distance as compared to the 60 series stock tire aspect ratio.

What will make my decision easy: Can the odo and speedo can be reset to the new tire size, for -sure-?

I suppose that this is a bit like going to 14" wheels as Sid mentioned in another thread. You get more performance and beat those xb's with beautiful big- rims, CAI, MOMO, and all that in drags down the boulevard, right?

Going with a lower profile tire will not "regain" suspension travel. That is reduced by your shortened springs, and has nothing to do with tires.

Yes, I understand that now. But can the odo/speedo be tuned to various tire diameters?

thanks for the help

If you go with a 215/50R15 the tire height should be about the same 23.5 vs. 23.7 so no other work is required.

I met someone today that said he had his odometer recalibrated at a local speedometer shop. The dealer told me some time ago it can't be done. I'll have to check it out further.

Walt

Thanks Rocket, but because I really don't want wider tires, but lower sidewalls, and am on 6.5" wide steel rims, is the reason why I phrased it this way.

I don't much want wider tires even though they -sure do look better-.

Newtmaker: thanks for that. Ya know, with the fact that everything is electronic today, we can fairly expect that the programing -might- be adjustable. Heck, every bicycle cyclometer is widely adjustable. Why not with cars too? So many tire sizes and rims!

best regards, and please update if you learn more,

reid

I checked with the speedo place. Apparantly someone was blowing smoke as the manager was very emphatic that the speedo/odo cannot be recalibrated in almost all the newer cars because they are controlled by a computer. Some are capable of being reprogrammed but very few. The Scion is one that cannot, as far as his equipment goes.

Walt

Ah, reality check! Well, thanks for this clarification just the same. Darn! :doh:


I live in a area perfect for summer tires 'year round. Here's my current tire of interest for the 15" steel wheels.

http://www.tirerack.com/tires/tires.jsp?tireMake=Goodyear&tireModel=Eagle+F1+GS-D3

Goodyear Eagle F1 GS-D3
195/50VR15

-instead of- 185/60/15


It appears to be a tire of superb dry and wet traction. The pattern is good looking,
http://img56.echo.cx/img56/6306/screenshot0595xz.jpg (http://www.imageshack.us) And the price in the mentioned size is only $89 online.
http://img53.echo.cx/img53/3873/f12en.gif (http://www.imageshack.us)


----Question: How much smaller is the Eagle F1 in this size, than the stock tire?
Please, how much more speedo error does this make? (I read somewhere that our 60 series stock tires produce an error, already... because they are a bit shorter than the 65 series tires for which the bB was designed)



How the F1 came about
http://www.goodyeartires.com/about/news/roost.html


why i want this: not real wide, to keep the rolling resistance down. Lower aspect ratio to reduce roll. Smaller diameter gives a slight gearing-down=equals better acceleration. Better appearance, inexpensive ( thrash-able), and lowers the car a smidgeon further.. but most of all: better handling on a budget. Am of the preference for mods in keeping with the modest price of the xB and its utilitarian basic nature.

Lucky me. I found that nifty tire size calculator program by looking for it again. Thanks to whoever found this service and posted it up originally.

http://www.miata.net/garage/tirecalc.html


the proposed change in tire aspect does this. the white area shows the height of the 60 series stock tire. This is a 65 series in Japan, right?

question: what is our speedo error with these USA stock-sized tires?
because I am having a speedo dial made up soon, and might as well have the speedo correction made at the dial figures, because the computer is not adjustable The odo will be wrong, but I can live very easily with that.

http://img260.echo.cx/img260/9202/screenshot0607vc.jpg (http://www.imageshack.us)

( a Gadwin PrintScreen screenshot)


Gadwin is a free software program. It's a great utility tool
http://www.gadwin.com/printscreen/


Hey, correct me if I'm mistaken, but this smaller radius gives a five percent power increase.
Will spin the rpms a bit higher, but also, the car will scoot quicker
Not a bad trade overall.
Wonder if the fuel milage would suffer much?
I don't suppose so. Work done, is work done-- it all much the same amount of fuel penalty imposed so long as we work near the peak torque.

As speed tools go, taller rims and bandy tire combos taller than stock do look stylish, but -are- a gearing-up, and so, reduce acceleration.

:nails:

FYI, the 195/50R15's are 22.7 inches in diameter, your O.E. size of 185/60R15 is 23.7 inches in diameter. The vehicle's computer will accommodate up to a 3% deviation without suffering and issues with the vehicle's speed odometer, odometer, ABS, and Traction Control functionally. Once you go outside of the 3% range, 22.98" in this case, you should have the computer reprogrammed for the new overall diameter.

Thanks, Roger. Concidental and convenient ,that the site from where I "borrowed" the picture ia your- firm's web page.


Here's a point to consider: Unless I'm mistaken, the xB design-center tire (bB Japan) is 185/65/15.

Therefore, our sixty series tires for the USA marketed cars already introduce mild error to thespeed/odo computer by this much:

http://img27.echo.cx/img27/3057/screenshot0612pp.jpg (http://www.imageshack.us)


now, if that is true, then my going down another aspect ratio step results in a more than double total deviation from design center:

http://img27.echo.cx/img27/8200/screenshot0620pr.jpg (http://www.imageshack.us)

hints so far given indicate that Scion's computer is not adjustable at all. That's a pity if its true.

How can we find out the real deal, from Scion? Who should I ask, please?

sent to Scion.com's email support center:

Urgently request reply ASAP
to this question detailed out at
http://www.scionlife.com/forums/viewtopic.php?t=64971

-IS the Scion's speedo-odo computer adjustable to correct for non-standard tire diameters?

Please reply to me directly, or more preferably, to the thread itself

I want to mount 195/50/15 tires to the stock steel wheels. This is a a smaller tire than the stock tire. The speedo error will be objectionable. I would like to adjust the car's computer to suit the actual tire size. How is this done?

please refer this question to a technical person who -knows for sure- if an adjustment can, or cannot be made.
Thanks,
SciFly at Scionlife

Was searching (dg!) for documentation which has previously established the stock-xB's speedo error, owing to the USA standard-aspect 60 series tires being -shorter in height than the standard tire size in Japan. If you have a direct pointer to -that- thead please show it here.


actually if you go with a 205/55-15 you'll get the added width, but your speedo will only be off by 0.6% instead of 4.0%

http://www.eunos.com/tirecalc/ check it out for yourself :idea:

However, the xB's speedo already reads 4% high (65MPH indicated equals 62.5MPH actual), so larger tires will actually correct the existing error! :)

I'm pondering 205/65R15s myself. Two inches larger in diameter, and a bit more sidewall to keep the hubcaps away from the curb.

George
from:
http://www.scionlife.com/forums/viewtopic.php?t=31457&highlight=speedo+error


another pertinent, short thread. no defining answer there, but interesting anyway
http://www.scionlife.com/forums/viewtopic.php?t=50855&highlight=speedo+error

my head is starting to hurt.
http://www.scionlife.com/forums/viewtopic.php?t=18976&postdays=0&postorder=asc&highlight=speedo+error&start=0

the F1's are on the way (195/50/15)
woOt, I like the tread pattern mucho

$89 x 4 = $356 + $42 Fedex

= minus= the Goodyear mail-in rebate of $60 per set of four,

= $85 per tire. Yeah, I know there are cheaper (chinese, etc) tires, but you get what you pay for, in general.

---Still no definitive answer about the speedo computer adjustability.
No word back yet from Scion; it will take a while.

If the computer can't be recalibrated I'll just use a GPS to make a steady-state speed check, figure the speedo error percentage from that

Chad Force is making for me a minimalist speedo face.

It looks like a -clock dial-
We can correct speedo error there in the dial face by moving the twelve hash marks around. Yeah, -12- hash marks and just... 0, 1, 2, 3 and so on up the scale.