new wheels ride height

[RiCeY]

The 50 indicates that this tire size's sidewall height (from rim to tread) is 50% of its section width.

So I was right? Im confused.

[aaronevolution]

You'd get the same answer without converting it to inches and then back to millimeters. That's just making more work for yourself and confusing the masses.

But us young people get confused by inches

[aaronevolution]

The 50 indicates that this tire size's sidewall height (from rim to tread) is 50% of its section width.

So I was right? Im confused.

I think that it's the top and bottom sidewall. So a 225/50 would have a 112mm sidewall, 56mm at the top and 56mm at the bottom (or sides)? I'll have to read more into it when I get home I think. I have confused myself.

[JuStDaN]

Here's my Vy with stock ride height running 245/35/19.



Will be lowered soon...

[ducker85]

you are just making that up i think. i just went from 17/45's to 20/ 35's and gained about 3.8cm. its pretty simple maths to work it out. i went up 3" in rim size (about 7 or 8 cm) lost 10mm tyre height. now to work out how much height i gain i half the rim size difference (because you only gain in height to the centre of the hub), then subtract the 10mm height difference in the tyres from that number. so therefore i was 3.9cm gain (from the rim), minus 10mm (tyre) = 3.8cm ride height gain.
i know for a fact because i just did it on my car today.
i cant understand why people are so certain it makes no difference to ride height......

p.s. i know its a thread dig, but i nearly made choices based on what is written here. so i felt it would be nice to ammend seing as it comes up in searches forever....

thats because your have the wrong tyre profile! I said 30 series on 20's the 35's are too large and illegal too. use a tyre calc online or go to your local tyre shop (I use the online tyre calc). good therd dig btw

as your rim diametre goes up your tyre profile goes down and the overall diametre stays the same if you choose the correct profile and width. So I am not making this up, especial as I use a online calc no mistakes in my maths buddy.

buy 245/30R20 and not 225/35R20 and you'll be fine

[RiCeY]

Its not always possible to get the exact same rolling diameter.

I went from 235/45R17s to 245/35R19s and the speedo read about 2kph higher.

[ducker85]

Its not always possible to get the exact same rolling diameter.

I went from 235/45R17s to 245/35R19s and the speedo read about 2kph higher.

there's a tolerance, legally I think its plus or minus 15mm. My stock VE Clubsport speedo is 4km out at 114km its doing 110km thats just a part of life.

when I went from 16's 225/55R16 i think to my 235/40R18s mine speedo got 2km slower, the 16's made it about 4-5km faster

[RiCeY]

yeah most speedos read a little high, after fitting the 19s mines spot on.

[slowandlow]

the out side diametre of your trye doesn't change from 15's thru to 20 inch with 30 series tyres so no your ground clearence wonth chage. It's a bullsh*t myth that people spread around however with lower profile tyres it creates the illusion that the gap between the tyre n gaurd is larger then before.

ok, but. even 20 inch with any profile tyre on it will increase the ride hight by over 3cm. my tyre is a 35 series. total height of the tyre is about 45mm. i gained about 380mm if i take the tyre off the rim completely ride height will still be higher than with 17" with a 45 series tyre on it. i promise.tyre height difference between a 30 series 20" and a 35 series 20" is stuff all mm in height. so, outside tyre diameter does change a heap from 15" to 20" a lot. i am only going on what i see, not what is written on the internet (which i havent read myself anyway).
simply, i put 20's on, my sideskirts sit 140mm from ground. i put 17's on it and the sideskirts are 100mm from the ground. this is my main point. the series of tyre wont make enough of a difference as to completely remove all your ride height gain. its impossible. how can 45mm (or less probably) of tyre height possible even out 350mm of rim height gain?

[TMM]

ok, but. even 20 inch with any profile tyre on it will increase the ride hight by over 3cm.

lol wut? You're probably getting different measurements from having different amounts of fuel or other things in your car or measuring it on a different surface, or your 17s were bald, and the 20s were new.
To increase the ride height by 3cm the wheel has to be a full 6cm larger.

20" wheels with the only legal tyre size (245/30R20) are only 4mm larger than 15" stockies, and smaller than Berlina 16". 17" are actually one of the smallest wheel/tyre packages so the car should sit lowest with those, but only by a few mm.

205/65R15 323.75mm
215/60R16 332.2mm
235/45R17 321.65mm
245/30R20 327.5mm

even if you had 245/35R20 which would rub to buggery on a commodore it's only 339.75mm - only 19mm increase in ride height over 17s. And maybe an extra 10mm max from going from completely bald tyres (belts hanging out and shit) to new ones.

[slowandlow]

im only posting what i measured a day or two ago. and im pretty competent with the tape measure. all this was done with about half a tank of fuel. i swear on my mothers grave that my ride height went from 100mm to 140mm (4cm) as a fact.
anyway. am getting kinda tired (haha get it...tyred) of trying to explain. if nobody beleives me thats fine by me. i dont really want to start a shitfight about it.

[aaronevolution]

im only posting what i measured a day or two ago. and im pretty competent with the tape measure. all this was done with about half a tank of fuel. i swear on my mothers grave that my ride height went from 100mm to 140mm (4cm) as a fact.
anyway. am getting kinda tired (haha get it...tyred) of trying to explain. if nobody beleives me thats fine by me. i dont really want to start a shitfight about it.

How wide are the 17's and how wide are the 20's?

[slowandlow]

How wide are the 17's and how wide are the 20's?

they are 245/45/17 and 225/35/20

[RiCeY]

If those sizes are correct the 20s will be 13mm taller than the 17s.

You sure the 17s werent 235/45? Thats the normal commo size... If they were the 20s will be 22mm taller.

[ducker85]

they are 245/45/17 and 225/35/20

245/45/17's measure up with; 110.2mm sidewalls, overall diameter of 652.3mm and a circumference of 2049.3mm rev's per km of 488

225/35/20's measure up like; 78.8mm sidewalls, overall diameter of 665.5mm and a circumference of 2090.7mm rev's per km of 478

this is fact form a tyre calculator now if you go and buy the profile I suggest of 245/30R20 lets compare

245/30R20 measure up like' 73.5mm sidewalls, over diameter of 655mm and a circumference of 2057.7mm with rev's per km of 486

now thats pretty farking close to the 17's and will not change your "ride height" by more then 3mm depending on ground surface and springs settlement. do I need to carrying on more?

here's the link to the tyre calc I used have a play with it. Tire size calculator sorry for being a prick but I've spent hours looking into this crap and know when im right

[slowandlow]

i know what i am seeing with my eyes and a tape measure.
lets just agree to disagree about my ride height. its no skin off my nose if you and whoever else dont beleive me. and im NOT saying the tyre calculator is wrong either..... i guess ill never know, playing with calculators doesnt really grab my interest.

[ducker85]

thats cool mate maybe the springs haven't settled down completely from when it was on the jacks? I can't tell you any more then it shouldn't be a wheel issue. I know mine car dropped another 10-15mm over night when I lowered it the other month.