hi guys just wondering does any one no i i fit 19s wat is the go with the speedo as the car has 15s on it now and i have heard that the speedo will under (egthe speedo says 60 and its more like 70) any ideas and wat does it cost to fix it?
Hi, If your speedo is correct now (with 15"s) just make sure that the "external" diameter of the 19" tyres you will put on have the same "external" diameter of you current tyres: for e.g.: stockies generally are: 195x65x15 -- meaning: 195 mm wide x 65% of width height in the walls of the tyre x 15inch rim. So total external diameter = 15inch (367.5mm) + (65% of width(195mm) x two walls each side of the rim) = 367.5mm + (126.75mm x 2 walls each side of the rim) = 621mm ----- So just make sure that the tyres you fit onto 19" rims are something like 225x35x19 tyres. Because; = 465.5mm(19" rim) + 35% of width of tyre (225mm) = 465.5mm(rim) + (78.75mm x 2 walls each side of the rim) = 465.5mm(rim) + 157.5mm(total of both tyre walls) = 623mm "external" diameter, This means the tyre is 2mm larger, which is fine because it will make your speedo out by just under 0.001%/per kilometer (nothing) You can use the same formula for working out any wheel/tyre combo. or just refer to the table i made up below for you. Rim Width Ratio External Diameter (inches) (mm) (%) (mm) 18 185 50 626 18 190 50 631 18 195 45 617 18 200 45 621 18 205 45 626 18 210 45 630 18 215 40 613 18 220 40 617 18 225 40 621 18 230 40 625 18 235 40 629 18 240 40 633 18 245 35 613 18 250 35 616 18 255 35 620 18 260 35 623 18 265 35 627 Rim Width Ratio External Diameter 19 185 40 614 19 190 40 618 19 195 40 622 19 200 40 626 19 205 40 630 19 210 35 613 19 215 35 616 19 220 35 620 19 225 35 623 19 230 35 627 19 235 35 630 19 240 30 610 19 245 30 613 19 250 30 616 19 255 30 619 19 260 30 622 19 265 30 625 Rim Width Ratio External Diameter 20 185 35 620 20 190 35 623 20 195 35 627 20 200 35 630 20 205 30 613 20 210 30 616 20 215 30 619 20 220 30 622 20 225 30 625 20 230 30 628 20 235 30 631 20 240 30 634 20 245 25 613 20 250 25 615 20 255 25 618 20 260 25 620 20 265 25 623 so that your speedo doesn't get effected, you will want to choose a wheel/tyre combo that keeps the 'external' diameter similar to your current tyres. hope that helps Cheers JA2Z
As JA2Z said, as long as your rolling diameter is the same it won't affect your speedo. In otherwords, bigger rims run lower profile tyres to achieve this. If you do find your speedo is out, a Jaycar speedo corrector can be installed to fix it.
hey guys thanks for the info well just waiting for them to turn up a mate has them and im like a kid waiting for christmass lol
Hey mate one quick question, Do you have any idea on how much one of them is going to set me back? as it might be a cheaper solution to my problem. Thanks
