Just got home from the tire mounting job.

F1's 195/50/15 L and R front and a size comparison with the standard 185/60/15 LS tire (unmounted)





These tires are not domestic manuf. They were made in Germany

If you want this size, and order from TireRack.com you must say they are for, say, an Xa, not an xB. Legal considerations disalllow them to sell a tire even slightly lower load cap. than the OEM tire. In this case, 1040lbs vs. 1100 for the OEM tire. Big whoop.

The traction rating of this summer street tire is not "A", but "AA"
treadwear rating 280 and temp "A".

These are going to be rougher riding by far than stock tires. That's OK. I am happy to trade ride for a stiffer sidewall and superb wet/dry pavement adhesion.

Also, the smaller diameter of the tire (radius, really) means faster acceleration. More torque to the road across the whole band. A five percent gear-down ratio.

 

I have the same tires on my car in 17". Great tires with superb wet traction. You made a good choice.

 

I hopethe car is lwoered, I have a feeling a smaller diameter tire on a stock height xb would look tacky I guess it is cool performance wise, but what kidn of power differences would be made at the track, if any? Cool, different imported mod though

 

wow, you're not kidding when you said it was smaller. maybe its just the pic or something, but the F1 looks dwarfed by the stocker!

 

Of course the tire is going to look smaller considering that he went from a 60 series tire to a 50 series tire. Plus the old stock tired isn't mounted either. I do like the tread pattern though.

 

Right- the unmounted tire is also slightly in the fore of the F1 so that makes it look even taller.

The difference in mounted height is one inch

The difference in appearance by "eyeball" is -huge- ; the sidewall is so much shorter.

The tires aren't broken in yet but I must say, now that I put the pressure at 30PSI instead of 40 like I had them yesterday-- -the ride is just fine.

first impressions:

-ride is smooth on moderately rough pavement
-big holes and some bumps do toss the car more than before
-the steering response is improved
-tire noise is similar to the LS
-tread noise when braking hard is absent; unlike the LS
-traction is superb compared to the LS

-the lower sidewall means less tire roll, of course. It feels so good to wiggle around the corners now.

-the car gap of the unlowered B looks -worse- with these shorter tires. I want to lower asap but the springs are on backorder at the factory.


-I will just chop down my stock springs fro the time being.
I wonder I I can drop 2.5" or 3"? Am only afraid of hitting speed bumps, slopes and of course, curbings. Is three inches drop from stock height too much for daily driving?

general question:
How much drop would -you- think is practical for a daily use B? At what drop do we begin to get bumps and scrapes at the nose? The number I really want is the undernose-to-street dimension so I can figure how much spring to lop off for a trial, while I wait for Goldlines.


By butchering the stock springs I can get a trial run on the new height and know that it works and looks good. Then if I get purpose-made lowering springs I'll know how much more to chop them if at all

 

toyo ti-s are better imo
the falken gr beta 451 is great for the price

 

Wow, one inch is a LOT of difference you know!

Have you calculated how far off your spedometer is now?

 

The speedometer is 6.1% off
when you are going 60 your speedometer will read 56.3

 

got that number here
http://www.miata.net/garage/tirecalcold.htmlenjoy

 

Yes, thanks. Chad Force is gonna make me a new dial face after I determine the true speed error.

It appears that the Scion odo/speedo computer is not adjustable.
Rather than work from calculations for the new dial's re-setting of the marks, I think I'll do some GPS measurements at steady speeds.

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Let's find and post pictures of equivalent-tread tires then. Thanks for that tip, too.
Cheaper is better, yes, if the quality is up there! for sure!

I like that -these- tires were made in Autobahnland (germany)

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Just tried a couple of quick stops on damp asphalt pavement. This is a rough test.

From 20 MPH to full stop was gotten in 3/4 of the car's length. No tire noise. Only light action from the ABS system.
This car with these tires stops faster than I have ever experienced before. (have not been in fast-stopping cars, really, other than the old Subaru SVX I used to drive.

 

Toyo T-1S is obsolete but is still available from stock. I like this look but I like the F1 tread a little more, for the appearance I mean.



a screen shot showing the old and new Toyo T...S, and the new R that replaces it. I like the new tread-look a little less again.

 

hey, thanks for that. Presuming that the xB's speedo is actually attuned to a 185/65/15 (the JDM stock OEM tire) then, here, the error is considerable:

 

I would def have gotten a wider tire like a 205/50/15 wouldda still been smaller but alot closer than 195.

 

Good point but I wanted to keep the tire narrow as possible and keep that sidewall low as it is.

See, I want the smaller radius so I can accelerate faster. The width of this tire with it's sharp tread patter (flatter face, too) and low profile makes it look -just fat enough- for a sport appearance.

The wheel gap is awful now. But I will go measure some local speedbumps and parking ramps to see how low I can dare to chop the exisiting springs down in height. I'd -like- to lower it three inches but this may be pushing the nose into bumps and ramps.

Most of all: unsprung weight stays down this way. And acceleration -is- notably better.

I wonder and feel pretty confident stating that no CAI or other bolt-on passive speed equipment like a Borla, etc. could give this much more torque-to-the-wheels. (corrections please) And this gain by lowering the final drive ratio is flat-even across the rpm board.

I'm liking this tire size very much and cun't imagine ever putting 60 series or any -taller- sidewall tires back on again. This sidewall height really helps the cornering stiffeness, you see? I get less ride cushion. It's about as low a sidewall as, say 40 series wideface tire on a much larger rim. Increasing wheel diameter, of course looks great but bogs the car down.. all the costs are greater and nothing is really gained but a fine appearance that most everyone wants nowadays.

to Darren

 

those look nice. look like they would handle a lot better then the stocks

 

hey, thanks! I did some major swerving on the empty I last night in the rain and -oh wow- now I see why corner carving gets into peoples blood. I like this security of knowing I can jerk around an obstacle and make no noise, no grrrr of tires. Is nice.

So are you for poking in here. Thanks for your input. Valuable to me because I'm so green at Scion stuff.

 

Hey there. Yes, the car looks awful right now because it is not yet lowered. The gap is hideous. Will get dropped in time. Am more excited about a lower CG than even the appearance factor. Coilovers? Maybe. Need to learn about this stuff.

other main question:
Nearly 10% power increase (at the road wheels) over, say, a similar B with tuner tires of 245/40/17. That tire is about a half inch greater radius than stock and mine is a half inch smaller R than stock.

zipp! stop! over bumps with ease 'cause the unsprung weight is still within one pound of the stock wheel and stock tire. (F1 is one pound heavier)

appearance suffers, sure, but all else goes up and -no one wants to steal my tires/wheels-


best regards and happy B'ing

 

Changing the tire diameter will CHANGE the vehicle speed for the same motor RPM!

This ALTERNATE tire size will change the actual vehicle speed to

62.09mph, when the odometer reads exactly 65mph.

 

Going with a lower tire sidewall profile would make the speedo read faster than your actually going i thought? To cover the same distance the smaller wheel would have to roll more than the "taller" wheel therefore making highway driving even worse?