18" - West Coast Fieros Forum

I've heard that the largest rim the Fiero can handle is 17", however a local car shop is selling a BEAUTIFUL set of 18" rims for only $400 (they include tires). Does anyone know if it's possible to run that large a diametre on a stock suspension and body set-up?

Never shift into reverse without a back-up plan.

Okie dokie. They're pretty low profile, so it might work. I'd better check the width I guess though. Thanks for the advice! =)

Never shift into reverse without a back-up plan.

This 18 is almost an exact match for the stock 15" lace wheels.

Dimensions

Dimension Tire A: 215/60 R 15 (25 x 8.46 x 15) Tire B: 225/40 R 18 (25 x 8.86 x 18) Difference

Width

Sidewall height

Overall height

Circumference

8.46"	(215.00mm)
5.08"	(129.00mm)
25.16"	(639.00mm)
79.03"	(2007.48mm)

8.86"	(225.00mm)
3.54"	(90.00mm)
25.09"	(637.20mm)
78.81"	(2001.82mm)

+0.39"	(+10.00mm)
-1.54"	(-39.00mm)
-0.07"	(-1.80mm)
-0.22"	(-5.65mm)

Speedometer Error

Actual Speed	Indicated Speed with Tire B	Speedometer Error
`5 mph (8.04 kph)`	`5.01 mph (8.07 kph)`	`+0.01 mph (+0.02 kph)`
`10 mph (16.09 kph)`	`10.03 mph (16.14 kph)`	`+0.03 mph (+0.05 kph)`
`15 mph (24.13 kph)`	`15.04 mph (24.20 kph)`	`+0.04 mph (+0.07 kph)`
`20 mph (32.18 kph)`	`20.06 mph (32.27 kph)`	`+0.06 mph (+0.09 kph)`
`25 mph (40.23 kph)`	`25.07 mph (40.34 kph)`	`+0.07 mph (+0.11 kph)`
`30 mph (48.27 kph)`	`30.08 mph (48.41 kph)`	`+0.08 mph (+0.14 kph)`
`35 mph (56.31 kph)`	`35.10 mph (56.47 kph)`	`+0.10 mph (+0.16 kph)`
`40 mph (64.36 kph)`	`40.11 mph (64.54 kph)`	`+0.11 mph (+0.18 kph)`
`45 mph (72.41 kph)`	`45.13 mph (72.61 kph)`	`+0.13 mph (+0.20 kph)`
`50 mph (80.45 kph)`	`50.14 mph (80.68 kph)`	`+0.14 mph (+0.23 kph)`
`55 mph (88.50 kph)`	`55.16 mph (88.74 kph)`	`+0.16 mph (+0.25 kph)`
`60 mph (96.54 kph)`	`60.17 mph (96.81 kph)`	`+0.17 mph (+0.27 kph)`
`65 mph (104.58 kph)`	`65.18 mph (104.88 kph)`	`+0.18 mph (+0.30 kph)`
`70 mph (112.63 kph)`	`70.20 mph (112.95 kph)`	`+0.20 mph (+0.32 kph)`
`75 mph (120.67 kph)`	`75.21 mph (121.02 kph)`	`+0.21 mph (+0.34 kph)`
`80 mph (128.72 kph)`	`80.23 mph (129.08 kph)`	`+0.23 mph (+0.36 kph)`
`85 mph (136.76 kph)`	`85.24 mph (137.15 kph)`	`+0.24 mph (+0.39 kph)`
`90 mph (144.81 kph)`	`90.25 mph (145.22 kph)`	`+0.25 mph (+0.41 kph)`
`95 mph (152.85 kph)`	`95.27 mph (153.29 kph)`	`+0.27 mph (+0.43 kph)`
`100 mph (160.90 kph)`	`100.28 mph (161.35 kph)`	`+0.28 mph (+0.45 kph)`
`105 mph (168.94 kph)`	`105.30 mph (169.42 kph)`	`+0.30 mph (+0.48 kph)`
`110 mph (176.99 kph)`	`110.31 mph (177.49 kph)`	`+0.31 mph (+0.50 kph)`
`115 mph (185.03 kph)`	`115.32 mph (185.56 kph)`	`+0.32 mph (+0.52 kph)`
`120 mph (193.08 kph)`	`120.34 mph (193.63 kph)`	`+0.34 mph (+0.55 kph)`
`125 mph (201.12 kph)`	`125.35 mph (201.69 kph)`	`+0.35 mph (+0.57 kph)`
`130 mph (209.17 kph)`	`130.37 mph (209.76 kph)`	`+0.37 mph (+0.59 kph)`
`135 mph (217.22 kph)`	`135.38 mph (217.83 kph)`	`+0.38 mph (+0.61 kph)`
`140 mph (225.26 kph)`	`140.40 mph (225.90 kph)`	`+0.40 mph (+0.64 kph)`
`145 mph (233.31 kph)`	`145.41 mph (233.96 kph)`	`+0.41 mph (+0.66 kph)`
`150 mph (241.35 kph)`	`150.42 mph (242.03 kph)`	`+0.42 mph (+0.68 kph)`
`155 mph (249.40 kph)`	`155.44 mph (250.10 kph)`	`+0.44 mph (+0.70 kph)`
`160 mph (257.44 kph)`	`160.45 mph (258.17 kph)`	`+0.45 mph (+0.73 kph)`
`165 mph (265.49 kph)`	`165.47 mph (266.23 kph)`	`+0.47 mph (+0.75 kph)`
`170 mph (273.53 kph)`	`170.48 mph (274.30 kph)`	`+0.48 mph (+0.77 kph)`
`175 mph (281.57 kph)`	`175.49 mph (282.37 kph)`	`+0.49 mph (+0.80 kph)`
`180 mph (289.62 kph)`	`180.51 mph (290.44 kph)`	`+0.51 mph (+0.82 kph)`
`185 mph (297.67 kph)`	`185.52 mph (298.51 kph)`	`+0.52 mph (+0.84 kph)`
`190 mph (305.71 kph)`	`190.54 mph (306.57 kph)`	`+0.54 mph (+0.86 kph)`
`195 mph (313.75 kph)`	`195.55 mph (314.64 kph)`	`+0.55 mph (+0.89 kph)`
`200 mph (321.80 kph)`	`200.56 mph (322.71 kph)`	`+0.56 mph (+0.91 kph)`

If your speedometer has been calibrated for 215/60 R 15 (25 x 8.46 x 15) tires, replacing them with 225/40 R 18's (29 x 8.86 x 18's) would result in the speedometer reading high by 0.28%.

Odometer Error

Actual Mileage	Indicated Mileage with Tire B	Odometer Error
`1 mi (1.61 km)`	`1.00 mi (1.61 km)`	`+0.00 mi (+0.00 km)`
`5 mi (8.04 km)`	`5.01 mi (8.07 km)`	`+0.01 mi (+0.02 km)`
`10 mi (16.09 km)`	`10.03 mi (16.14 km)`	`+0.03 mi (+0.05 km)`
`50 mi (80.45 km)`	`50.14 mi (80.68 km)`	`+0.14 mi (+0.23 km)`
`100 mi (160.90 km)`	`100.28 mi (161.35 km)`	`+0.28 mi (+0.45 km)`
`500 mi (804.50 km)`	`501.41 mi (806.77 km)`	`+1.41 mi (+2.27 km)`
`1000 mi (1609.00 km)`	`1002.82 mi (1613.55 km)`	`+2.82 mi (+4.55 km)`
`5000 mi (8045.00 km)`	`5014.12 mi (8067.73 km)`	`+14.12 mi (+22.73 km)`
`10000 mi (16090.00 km)`	`10028.25 mi (16135.45 km)`	`+28.25 mi (+45.45 km)`
`50000 mi (80450.00 km)`	`50141.24 mi (80677.26 km)`	`+141.24 mi (+227.26 km)`
`100000 mi (160900.00 km)`	`100282.48 mi (161354.52 km)`	`+282.48 mi (+454.52 km)`

Capt Fiero
88 Fiero GT 5spd V6
Eight Fifty Seven GT V8 5spd.