futuregs

A boy of mine (the dude witht he 240sx) and I just had a debate on this regarding tires.

If he puts a 30 series tire on 18's he claims his speedometer will be off ever so slightly (few mph) I said it would be off by more than just a few.

Who can answer this question for me?

Thanks

pot_head

I think you need the overall height of his stock wheels/tires to figure out this question. Im sure wheel gurus can answer this one quickly but the need the stock rim size and stock tire size.

futuregs

his stock wheels were 15's i believe and they had a profile of 55. Not sure of the other #'s

SoCalSC4

Need more data...

Are you working on his 240SX or your Lexus?

futuregs

Here it is
Here was his old stock wheel size

205/55/16

Now he has 18's
dunno that size yet.

But he trhought a 30 rated tire on an 18 wheel wont make much difference in odometer change.

Manaray

Hehehe....285...maybe on a widebody 240SX...

Compared to the stock 205/55-16...

If he does a 225/30-18, he'll have a 6.3% speedo error (60MPH on the speed will actually be 56.2)

A 245/30-19 will give him a 4.4% speedo error (60/57.4)

Tell your friend to get his head out of his ***...what is the reason for doing 30 series when you don't need to? Maybe on 19's...but on 18's?