18"by7.5" and 245/45/18 tires combination will fit '99 i30??
I got H&R springs and GR2 shocks which ready to install.

one more thing! ....What If I install the H&R lowering spings with stock 15" wheels and tires, any problems to drive around NYC? (hitting bumps, pot holes..etc)

I really wanna know....help me guys,

 

you need to know what the offset is.

245/45/18 tire is kind of tall. most ppl use 245/40 on 18x8.5" wheels

 

-----------------------------------------------------------------

off set is 40mm. this wheel is 2004 Maxima stock one.
you think drive with 15" wheels+lowering is fine??
Thanks anyway.

 

That size tire will make your speedo off, it's the wrong diameter.

15" wheels + lowering is fine, won't look as good but it's fine.

 

Thanks for your reply.
then, what's the good tire size for 18" or 17" Nissan oem rims for my
i30??

 

i have 235/40/18 with 18" wheels. looks perfect with lowered car. 245/45/18 is too tall

 

I30T, what do u mean by it will make your speedo off, the speed that shows up on the speedometer wont be correct?

 

No it won't. When you change the diameter of the tire you essentially change the gearing. Too small and your speedo will read fast, too tall and it will read slow.

 

so 225/45 R18, 245/45 R18, on something like a Infinti I30(96), would be affected in this way? is there any way to fix it?

 

Get the correct size tire, although being one size too small or large will make only a small effect on the speedo and only at higher speeds will it be noticeable.

 

Out of curiosity, just how much of a difference do u think it would make, lets say for example taht you are doing 100 km/h, what do you think it would show up as on the speedo

 

don't listen to the others...245/45 will be fine...but replacement tires are quite expensive in that size

 

it will make the speedo off, that is just a fact

 

I have heard that if you go one size larger ie:40-45, you speedo will read something like 5 percent slower.

I would just go with the correct size tire, 245/40/18, and try to avoid potholes.