Bigger rims

[lautray]

When going up to a bigger rim size ie from 17" to 18"/19", do you have to lower the car to maintain same ride height? Or does the lower tyre profile offset the increased diameter? I think the difference between 17/18/19 inch diameter with 45/40/35 profile respectively, is negligible?

[seldo]

yep. that's the theory anyway. Some manufacturers don't follow exactly though and there can be a big difference from manuf to manuf in terms of profile. It's a good idea to check their web-sites although not all are as comprehensive and don't give specs. When I bought new wheels/tyres for my missus' car recently I didn't even rely on the manuf's specs - I put a tape around them to check on the rolling diameter. Also of course - the same size tyre on different rims will give a different result...

[BOMI]

What Seldo said Erik!


Troy :)

[DaveHAT]

When going up to a bigger rim size ie from 17" to 18"/19", do you have to lower the car to maintain same ride height? Or does the lower tyre profile offset the increased diameter? I think the difference between 17/18/19 inch diameter with 45/40/35 profile respectively, is negligible?

Erik,

I stood one of my new poofta rims up against one of the 17s and the rolling diameter was within a bee's dick of being the same. Also worth noting is that the ppk dash setting for 17" rims is 6301 whereas 18" is 6300 ... huuuuuuuuuuuuuuuuuuuuuuuge difference. So I think your negligable thinking is pretty on the money.

Since putting the 18's on mine the ride height looks exactly the same (and the brakes now look tiny :( ) That's just my experience with it anyway but best way is to stand a 235/45/17 next to a 234/40/18 and see how they compare.

[chilly]

Erik,

I stood one of my new poofta rims

are they the ones with bigger holes or longer studs :whip:

[seldo]

You'd be surprised how difficult it is to accurately detect a difference in height by standing the 2 side-by-side because the two tyres rarely will stand up by themselves and different wear patterns / inflation pressures / new/old etc all make a difference. I doubt that you can tell the difference to within 5 - 10mm accuracy. Just ask a couple of your mates to go and measure the height of the front tyre on your car - 3 mates = 3 different measurements. And 10mm you would think is SFA, but it equates to about 30cm difference in rolling circumference. A tape around the outside is the only accurate way. :yep: