i have stock shooters now, im getting 17x8s with 275 40s or 45s i m not sure... how far off will my spedo bee?

 

to know exactly-

[17 + 2(275*.4)/2.54] / [16 + 2 (245*.45)/2.54] * speed

or

Just a few mph

 

You shouldn't put 275's on an 8" wide rim - serious mistake. Most tire manufacturers recommend no smaller than a 9" wide wheel for a 275. It will cause the tire to bulge at the sides, cause excessive sidewall flexing, bulging of the tread, overheating....

If you use a 275/40-17, it will be exactly the same outside diameter as the stock 245/50-16's, and there would be no effect on the speedo. If you get 275/45-17 (is there such a size??) you will have a speedo that reads 4.5% lower than actual speeds... at a true 60mph your speedo will read 57.5mph.

You might want to think this through.....

 

there actually the wheels off robvas car, they have 275s on em allready... soo ima leave em on there and see what happens

 

he seemed to have no problem soo.. ill do that