Speedo: How off with 33s?

spressomon

glutton
Moderator
 
Joined
Jan 9, 2005
Messages
12,635
Location
Northern Nevada
macneill said:
What is difference in mph with 33s?

Not that Grandpa here rarely goes above what I think is 65, but was just wondering how off it is.
Mac,
With my 285R75 16 GY MT/R's the actual difference (GPS) is 5%. So at 65mph the actual speed is 68mph (actually 68.25).
 
Joined
Apr 2, 2005
Messages
14
Location
Los Angeles, CA
I had mine checked a few years back, but I remember that there was a 12-13% difference with my FJ60. I have 33x12.5x15. So when it shows 65mph on my speedometer, I am actually going about 75mph... Hope this helps..
 

hoser

SILVER Star
 
 
Joined
Dec 21, 2003
Messages
9,245
Location
Bay Area, CA
If one didn't have a GPS...

33"/31.3"=1.05
A 5% increase given the speedo is accurate in the first place.
 

spressomon

glutton
Moderator
 
Joined
Jan 9, 2005
Messages
12,635
Location
Northern Nevada
Remember "31", "33" etc. is nominal dimension...ultimately the actual circumference may differ slightly for each brand/model of tire.
 

Cruiser_Nerd

That 25 Guy.
Moderator
 
 
 
Joined
Dec 3, 2002
Messages
4,279
Location
Higganum.
mheredia2930 said:
I had mine checked a few years back, but I remember that there was a 12-13% difference with my FJ60. I have 33x12.5x15. So when it shows 65mph on my speedometer, I am actually going about 75mph... Hope this helps..
This would make sense, as I think stock tire size on the 60 was a 235/75/15 The 100 would be seeing a smaller difference because of the taller OEM tire. :)
 

tabraha

Hello My Name is: TAD
SILVER Star
 
 
Joined
Aug 20, 2003
Messages
2,528
Location
South Carolina
spressomon said:
Mac,
With my 285R75 16 GY MT/R's the actual difference (GPS) is 5%. So at 65mph the actual speed is 68mph (actually 68.25).
Pretty much what I get too when I have the 285/75R16 Revo's on.
 
Top Bottom