323F @ Fondmetal/Radius R2 205/40R17

[TStar]

after an odysee i got them finally installed today (yes, wheelhouse borders had to be crimped).
the lug nuts were ordered from italy (3 weeks to arrive!), tuev inspector made mistake with certification etc.. i don't want to bore you with the details, just 2 of them:

- my car now sits about 3cm higher(!) than with my winter ríms (which sucks)
- all in all installation material+costs = 290€ ...... i feel no happiness today. (monkey)

http://mazda.taillandier.de/private/mazda_323_17inch_may2005_1.jpg
http://mazda.taillandier.de/private/mazda_323_17inch_may2005_2.jpg
http://mazda.taillandier.de/private/mazda_323_17inch_may2005_3.jpg
http://mazda.taillandier.de/private/mazda_323_17inch_may2005_4.jpg
http://mazda.taillandier.de/private/mazda_323_17inch_may2005_5.jpg
http://mazda.taillandier.de/private/mazda_323_17inch_may2005_6.jpg
http://mazda.taillandier.de/private/mazda_323_17inch_may2005_7.jpg

[twilightprotege]

nice clean wheels. i like.

if your car sits 3cm higher its not because of the wheels - you have the wrong sized tyre

[TStar]

it's the only size thats listed/allowed in the certificate for the car down here..... 205/40R17...

until this morning i had still my winter tires on..
185/65R14 ... usually during the summer i was driving
195/55R15... and now i'm driving
205/40R17

the larger my rims become, the higher my car is sitting (while my tire sizes are the "default" ones allowed here)... the winter tires brought the car down to the ground,looked really badass..the 15" alloys were nice but a but higher and the 17s make my car look like a suv 8)

i know this sounds absurd because i simply calc
185/65/r14 = 35,56cm (14inch) plus 12,02cm*2 (2x 65%of 185width) = 59,6cm in height
195/55/r15 = 38,1 plus 10,72*2 = 59,54...
205/40/r17 = 43,18 plus 8,2*2 = 59,58
and the results in the calculatory height is always prettymuch the same.. but still..what i stated above is a fact :(

or wait..do i have to multiply the height * 2 ? maybe not,but if not, then the results of the total height would become smaller the larger the tire gets.. oh dear, i will have to consider this again when i have slept 8h.. gnite.

[Dogo]

it means the overall diameter ( type + rim ) will be larger than normal.
this will make your speedo wrong ! it will be configured for the factory wheel circumference.

[BigBoyLemonade]

Your car looks really good! I love the wheels, it kinda reminds me of a porsche in a roundabout fashion...

[twilightprotege]

check this out : http://www.miata.net/garage/tirecalc.html

however, if 195/55/15 are your original tyres, 205/40/17 are the same size. if that's the case, it should sit higher....strange, very strange.

[TStar]

recalced....it didnt let me sleep 8)

185/65/r14 = 35,56cm (14inch) plus 12,02cm2=47,58cm in height (rim+tire)
195/55/r15 = 38,1 plus 10,72 = 48,82cm
205/40/r17 = 43,18 plus 8,2 = 51,38cm

that's the explanation.. my car DOES indeed sit 3,5cm higher than with the 14" rims.. although the overall running perimeter stays the same (with a very small tolerance)

that's wicked...ah, i must sleep lol

(hey twilight, i know this calc,it's widely spread in many variations..but it doesnt calculate results which suit reality...i heard people complain about this issue before...)

[twilightprotege]

i still dont get it!

the diameter of the tyre remains the same therefore the distance from the hub to the outside of the tyre has to remain the same. if that doesnt change then the height shouldnt change too. am i right?

i get what you're saying, but it just doesnt make mathematical sense.

ps - your car really needs a rear skirt to match the front bar and side skirts ;)

[Dogo]

yeh that cant be right. unless your type pressure has changed dramatically !

[twilightprotege]

either way - those are still very nice wheels.

[Rupewrecht]

i like it, subtle, and go well with the car

[nalawa]

TStar,

What you need to do is interpret the units correctly. The difference isn't in cm!!!

185/65 R14 = 596.1 mm (tyre + wheel diameter)
195/55 R15 = 596.5 mm (tyre + wheel diameter)
205/40 R17 = 595.8 mm (tyre + wheel diameter)

therefore the difference across these three tyre/rim combinations is:

0.3 mm

[chicaboo]

Or in German expressed as 0,3cm.

[tidy protege]

I like the car its a very tidy ride and the wheels suit the car nicely good work

[TStar]

nalawa
i made 2 calculations..
- the first calculation shows same results for all the rim/tire combinations (with a very small tolerance of a few milimeters)...that's the values all the tire calcs give you... but:
- the second calculation (which only takes 1 x the height of the tire) equals my factual experience...which basically says that my car came about 30mm/3cm lower to the ground wth my 14" rims and the according tires..

but i'll tell you what.. this morning i'm going to pickup my winter tires and i will put them directly next to the ones mounted on my car right now.. maybe i'll get enlightened

[nalawa]

Tstar,

Sorry mate your maths is correct but I think your logic flawed.

Tyre/Rim combinations effect your car height by half their combined diameter (radius), that is from the bit touching the ground to the centre of the axle (hub). (That is with tyres inflated to the same pressure)

Therefore to calculate the difference between each tyre/rim combination you need to add half the rim size and the tyre sidewall size. If you rework your second set of calculations using half the rim you will find that the diffference are half the variation found in your first calculation.

Only difference I can see is that your snow tyres either use a different measuring system (?), or maybe are inflated less that your summer tyres. This would cause the car to sit lower due to more sidewall spread.

[TStar]

this morning at the dealer's garage, i put the 14" winter wheels next to the ones mounted on right now (17)...
the difference in total height (standing next to each other) is not big,actually i would say, about 4-5mm... which means that it would be only 2-2.5mm difference from the center to the ground..which is nothing.

seems to me the only explanation could be the air pressure within the tire/how much they get "pressed" when the car is standing on the ground?.. weird situation though...i will definately try to find out if there is some difference or if it's just an optical illusion... i will look for a fixed point at the chassis when i put the winter tires on again..could take a while 8)