tirerack got our ride listed on their website! finally...

bad thing is that it automatically downgraded our tires to 195/65 15
and it does not have 15" steel rims for this size...

wierd... i thought "15x6 38mm 5x100" rims should be the correct ones for us to go for 15"
and they should have this size of steel rims in stock, since 2004 vw jetta has the same tire specs as ours, and its got suitable steellies to go for

 

Uhm our stock tire is 16" not 15". Or did I read this wrong and you want 15" on your car?

 

Too bad they recommend 215/40/18 and 205/50/17 tires for 18s and 17s. Not the size Toyota recommends.

 

Actually, the size they recommanded are closer to the specs of our oem tires.
205/50/17's diameter is 638 mm and 195/60/16's diameter is 640mm
which means that when the speedo is reading 60mph, the actual speed is 59.8mph ==> only a 0.3% error, far smaller than the 1% error tolerance

If I were to get new summer tires, I would go for 205/50/17, since it's the closest match.

 

I'm living on the snow belt, and it snows like hell every winter,
195/60/16 is almost impossible to find, except the pirelli scott zero 210 --> only sold on 1010tires, around 140 bucks per tire
205/55/16 has a 1.2% error on the speedo, which is a bit too much, and it would be a bad idea to use wider tires in the winter.... I'll need narrower tires to push my car through the snow
195/65/15, although not cool looking, is very practical ==> 0.8% speedo error, and only 65-70 bucks per tire.

My first choice would of course go with the oem size 195/60/16 winter tires, if any other website gets them at a cheaper price... 140 bucks per tire is just too much for me.

 

For 17 - yes, 205/50 is closer match than 215/45 that Toyco put on JDM iST, but 18s are a different story.

640mm stock tire vs 629mm their recommendation (almost 2% speedo discrepancy) while they could've put 225/40/18 that are 637mm and only 0.5% off.

 

Zoltiz, you LOVE these tire/wheel discussions!

Can we just get a tutorial and sticky it in the future?

 

There's just so much that's riding on the tires. Correct sizing helps with safety, handling, gas mileage, wear. For show cars it does not matter - if it fits - it's great. but for a daily driver you can't really afford to deviate too far from the manufacturer's specs. You screw up width and offset and you got yourself a sliced sidewall, you mess too much with overall diameter and your VSC/EBD/ABS might not do their job well in an emergency.

Hopefully if I keep reminding people that, they will take time to research before they buy wheels/tires.

The math is pretty simple behind it, but there is a ton of wheel/tire calculators. For tires my favorite is http://www.miata.net/garage/tirecalc.html

1010 Tires has a decent offset calculator:

http://www.1010tires.com/WheelOffsetCalculator.asp

Takes a minute to run your wheels / tires through them, but can save you $1K+ in cash or save your butt in a sharp turn one day.

 

I, for one, appreciate your input in the matter. I just figured you were getting tired of it.

 

^^^X2. This is all good info. So many people I know just look at the rim size, not actually research to see if the rim offset is right or the tire size should be used at all...