I drove a TR yesterday as I am looking for my first Fcar. The owner mentioned the speedo was off by 5-10mph. I noticed the tires were: Fronts: Yokohama Avid V4 P255/50R16 91V Rear: Yokohama Avid V4 P255/50R16 99V These are the exact numbers off the tires. They were not a low profile tire, but it handled terrific. Could these tires be the wrong size and that could be the reason the speedo is off? I thought Ferrari spec's 225/50 VR16. I am new to this site and find the site and members great! I could not find anything in the archives. Thanks in advance from a newbie.
Not sure about the front (seems too wide), but that sounds like the correct size for the rear. On Ferraris, the speedo sender reads off the transaxle. Most Ferrari speedos read 4-5mph high...so that is within the normal range. I wouldn't worry about it.
Hi........... Check out: www.miata.net/garage/tirecalc.html for a site with a speedometer error calculator. Only need to know the OEM tire size and the current tire size to get an answer. You can "fabricate" some numbers as well, to see what differences will generate 5-10 MPH errors. Check out specification tables at: www.tirerack.com for the overall diameters of different tires, which will predict speedometer error as well. Frank.........23005 www.masiarz.net/bb_resource
Are you sure that that front tire size isn't actually 225/50-16? 255/50-16 is the stock TR rear tire size for the 16" wheels (and my speedometer is over-optimistic too).
I read and double checked the size. The front and rears are 255/50/R16. The fronts end in 91V and the rears say 99V.
Dear Ferraristi, I have a 91 US Testarossa myself. Freeze...Miami Vice! Anyway, that front tire is too big. TR steering is uh well something already... it should be a 225/50ZR 16 My speedo also reads high about 5 mph. My 308 GTSI would read 10 mph high! I think you're ok.
