1995LS400

Ive driven next to alot of other cars in 35 and 45 mph zones, side by side, and noticed that the speedo seems to be off by +2-3 mph. Therefore Im going 37-38 to keep up in a 35, likewise 47-48 in a 45. Does this seem right, being that the overall height of a 245/50 is slightly lower than a 225/60?

Just to be **** about the whole thing, (I did take Trig and Physics in H.S.), I figured that the 225/60 will do 93 miles compared to the 245/50's 100 miles. But would it bother you, personally, if you added 7 extra miles to your car for every 100 that you traveled? I dont care, I just bought them because the profile looks alot better than stock. And the actual tread on the ground is almost 9 inches wide.

trukn1

Bigger the tire, the more likely the speedo will be off. The speedo is set based upon the stock specs for the tires on the car. Change the specs a little and off she goes. Only solution would be to have the speedo re-calibrated to the new tire specs (major PITA to do so!!!). Just be aware that your speedo is off due to the new tire specs and watch your speed when pushing the envelope. LOL!!

dfkd

According to {http://www.miata.net/garage/tirecalc.html your speedo will show 3.7% faster than you're really going. When your speedo shows 60 you're actually going 58.