rated:
posted: Jul. 3, 2008 @ 4:35p
neidermeyer said:
You can use either size ,, both were original equipment sizes ,, tire sizes are plus or minus 6% with the manufacturers... a 205 in one brand may be wider than a 215 in another brand... within a brand the sizing usually is consistant... In many Japanese cars the speedometer/Odometer runs FAST ,, this has been the subject of class action lawsuits against Toyota/Honda and Mazda as a fast Odo means your warranty runs out faster! ... putting a 185 on the car may actually put the Speedo/Odo closer to true ,, the best way to check accuracy is with a GPS unit giving actual realtime speed ... I would look at the "FET" on each tire ,, it is $0.10 per pound of rubber ,, more tax equals heavier tire that takes more power to spin... also look at the "revolutions per mile" number in the tire specs... I predict very little difference between the 175 and 185...
I see that a 1998-2002 Corolla has a digital Odometer ,, you can always get it adjusted by Dashpro.com 
Didn't know that about Jp manufacturers. How long ago? I wonder if that applies to the 98? I know my Miata isn't very accurate. My friend was following in his car w/ a GPS and my speedometer was about 5mph faster than what his GPS told him.
In regards to the size, I'd argue thatit's consistent even WITHIN a brand. I have a set of Falken ziex912 and rt615 in the same size. The rt615 are wider than the 912's even though both are supposed to be 225.
You're right in that it's not a whole lot of difference between the 175 and 185 in terms of RPM. But seeing how weak the Corolla is on power, every bit helps. I should know. I have an 89 Civic DX. 
Message edited by: yuletak on 2008-07-03 16:35:51 CDT