redvtec04

195/60/15 is my stock size, I tried 205/60/15 and the tire calc said my speedo would be off ??
tried 205/65/15 still off, tried 205/55/15 and it still shows a percentage off. Im keeping the same 60 size wich id the height so why would it be off??

Zzyzx

The 60 is the aspect ratio of sidewall to width, so a 205/50 is a different height then a 225/50. Examples: a 205/50-15 has a side wall height of 4.06 inches, where a 225/50-15 has a side wall of 4.45 inches.


a 215/55-15 is just .32% too slow
a 205/55-15 is 1.30% too fast
a 225/50-15 is aslo just 1.30% too fast


so for a wider tire a 215/55-15 would be your best bet. But even so, a 1% difference (Slow) only means that if your speedo says you are going 100 MPH in reality you are only going 99MPH. Its a persentage after all....

redvtec04

Cool thanks!

sitinduk

iTrader: (9)

If both tire/wheel combos have the same overall diameter, I think the speedo should be correct. I don't know how the Tire Calculator applet works, but the values I get by calculating sizes manually are a little off from the applet. Maybe I'm doing something wrong?
Here's what I got for yours:

(overall diameter = 2 * tire sidewall + wheel diameter)

stock: 195/60-15:
(2 * 195mm * .60) + (15 in. * 25.4mm/1 in.) = 615mm

----------------------------------------------------------
205/60-15:
(2 * 205mm * .60) + (15 in. * 25.4mm/1 in.) = 627mm

205/65-15:
(2 * 205mm * .65) + (15 in. * 25.4mm/1 in.) = 647.5mm

205/55-15:
(2 * 205mm * .55) + (15 in. * 25.4mm/1 in.) = 606.5mm
------------------------------------------------------------

So if you stay with 15 in. wheels, tire size (YYY/XX) will have to equal 195mm * .60 = 117mm.

eg. YYY * .XX = 117mm, let YYY = 205
.XX = 117 / 205 = .571
If they made a tire in 205/57-15, It would be almost dead on.
I would go with 205/60-15 or 205/55-15.
Hope this helped.

MIT

iTrader: (10)

oky, i got a question for my tires.

my stock size 185/70/14....but i want change to 205/55/15. which give me 1.30% too FAST.......some of tire experts said to stay with -3 or +3%.....

so if i traveling 1000miles on new tires, how many extra miles is goin to add up on my car? is 13 miles?

thanks,

NoLeadEmSoMuch

iTrader: (3)

New question:

18x8, offsets of +21 or +42, and a backspace of 5.33 inches...what the hell does this mean (I know the wheel size, but the rest), and will it fit a 7thGen LX?

sitinduk

iTrader: (9)

MIT, that's correct. Since your new tires (205/55-15) have a smaller diameter (606.5mm) than stock (185/70-14, 614.6mm), they will have to make more rotations to go the same distance. Since they're about 1.3% smaller, they will have to make 1.3% more rotations:
1000mi * .013 = 13mi.

NoLeadEmSoMuch, the offset is how much the mounting surface of the wheel is moved off center. If a wheel had 0 offset, its mounting surface (where it attaches to the hub) would be right in the middle of the width.
eg. A 15x7 wheel with 0 offset would have 1/2 of the width (7in/2 = 3.5in) of the wheel in the fender and the other half out of the fender.
Positive offsets move the mounting surface out of the car, Negatives move it into the car.
For 18x8 w/ +21 offset,
(8in / 2) + (21mm * 1in/25.4mm) = 4.827in of wheel will be in toward the car

For 18x8 w/ +42 offset,
(8in / 2) + (42mm * 1in/25.4mm) = 5.654in

This doesn't take into account that the tire will also stick out past the rim a little.

NoLeadEmSoMuch

iTrader: (3)

OK, thanks for all that, but no one has so far answered iif that size combo will fit.