Staggered tyre

[Johnny Pai]

Hi all expert,

Need some advice from you guys, planning to change my Reims from 17’ to 18’ staggered, was told the the front 235/40/18 and rear 255/35/18, was thinking to have the rear 255/40/18 and was told wrong match, wonder what’s was the reason, anyone here that can help? Much appreciate. 
 

thanks

[kepiting1sg]

On 9/21/2021 at 4:05 PM, Johnny Pai said:

18 and was told wrong match, w

255/40/18 has a bigger overall wheel diameter than 255/35/18 causing error in speedometer readings

[kepiting1sg]

255/35-18	255/40-18	Difference
Diameter inches (mm)	25.03 (635.7)	26.03 (661.2)	1 (25.5) 4%
Width inches (mm)	10.04 (255)	10.04 (255)	0 (0) 0%
Circum. inches (mm)	78.63 (1997.11)	81.78 (2077.22)	3.15 (80.11) 4%
Sidewall Height inches (mm)	3.51 (89.25)	4.02 (102)	0.5 (12.75) 14.3%
Revolutions per mile (km)	805.84 (500.72)	774.76 (481.41)	-31.08 (-19.31) -3.9%

Forum embed code: 

Speedometer Difference

Speedo Reading	Actual Speed
20 mph (32.19 km/h)	20.8 mph (33.48 km/h)
25 mph (40.23 km/h)	26 mph (41.85 km/h)
30 mph (48.28 km/h)	31.2 mph (50.22 km/h)
35 mph (56.33 km/h)	36.4 mph (58.59 km/h)
40 mph (64.37 km/h)	41.6 mph (66.96 km/h)
45 mph (72.42 km/h)	46.81 mph (75.33 km/h)
50 mph (80.47 km/h)	52.01 mph (83.7 km/h)
55 mph (88.51 km/h)	57.21 mph (92.06 km/h)
60 mph (96.56 km/h)	62.41 mph (100.43 km/h)
65 mph (104.61 km/h)	67.61 mph (108.8 km/h)
70 mph (112.65 km/h)	72.81 mph (117.17 km/h)
75 mph (120.7 km/h)	78.01 mph (125.54 km/h)
80 mph (128.75 km/h)	83.21 mph (133.91 km/h)
85 mph (136.79 km/h)	88.41 mph (142.28 km/h)
90 mph (144.84 km/h)	93.61 mph (150.65 km/h)
95 mph (152.89 km/h)	98.81 mph (159.02 km/h)
100 mph (160.93 km/h)	104.01 mph (167.39 km/h)

 

[kepiting1sg]

On 9/28/2021 at 11:21 PM, snsd555 said:

Ever so helpful, thanks @kepiting1sg! 255/35/18 would be the right match for the front.

You're welcome!