Will the alloy width affect the speedometer

[rpfletch]

Hi all,

 

I'm thinking of going 8.5'' 20 ET (tyre size would be 245/45R18) at the front and 9.5'' 20 ET (tyre size would be 265/45R18) rear would this affect my speedometer from standard size of fronts 8'' 30 ET (tyre size would be 225/45R18) and rears 8.5 30 ET (tyre size would be 245/45R18),

 

Would this have any affect on the speedometer?

 

Thanks in advance

[Guest]

Hi,

try this website and you should get any comparison you want.

https://www.tacomaworld.com/tirecalc

[KyleR]

Tyre width makes zero difference, however, since you appear to be keeping the 45 profile instead of dropping to 40 as most do, the circumference of the tyre will be larger and will affect the speedo. You will be travelling faster than the speedo says, which is basically begging for a speeding ticket.

[Guest]

Sorry Kyle, don't take this the wrong way, but they do, its all to do with the ratios, have a look at the website above.

Cheers

Andy

[Paul K]

try this website

 

http://www.willtheyfit.com

 

also refer to the Wheels section to find the correct ET for standard rims

[Aashenfox]

Sorry Kyle, don't take this the wrong way, but they do, its all to do with the ratios, have a look at the website above.

Cheers

Andy

 

Actually, he's technically right. The width of the tyre does not affect the speedo reading, the diameter/circumference/rollout does, it's up to the person increasing or decreasing the width to similarly make sure they don't change the diameter. Kyle is well aware that keeping the same sidewall ratio while changing width will result in a different diameter tyre, everything he said is spot on for purposes of the post.

 

To the OP, use a rollout calculator such as this one...

 

http://www.1010tires.com/Tools/Tire-Size-Calculator

 

...to help you work things out. Try your best to stick to stock diameters 225/45/18 and 245/45/18.

Edited February 13, 2017 by Aashenfox

[Guest]

HI,

Only going by the link i have put up, if you change the width of tyre and nothing else then the rolling speed, diameter changes, anyways as long as you use some sort of calculator you wont go far wrong

rpfletch

[AliveBoy]

HI,

Only going by the link i have put up, if you change the width of tyre and nothing else then the rolling speed, diameter changes, anyways as long as you use some sort of calculator you wont go far wrong

rpfletch

 

That's because the profile of the tyre is a percent of the width. For example, if you changed from a 200/70R14 to a 300/30R18 the speedo will only be 0.25% out. Width does nothing, alloy size and tyre profile do everything.

[rpfletch]

is their any way to get the speedometer corrected if it was out ?

[KyleR]

What they said ^^^^^

[Ekona]

is their any way to get the speedometer corrected if it was out ?

Yes, fit the proper size tyres

[brillomaster]

HI,

Only going by the link i have put up, if you change the width of tyre and nothing else then the rolling speed, diameter changes, anyways as long as you use some sort of calculator you wont go far wrong

rpfletch

 

That's because the profile of the tyre is a percent of the width. For example, if you changed from a 200/70R14 to a 300/30R18 the speedo will only be 0.25% out. Width does nothing, alloy size and tyre profile do everything.

 

I would have loved to see this on my wifes old Pug 206

[StevoD]

Hi all,

 

I'm thinking of going 8.5'' 20 ET (tyre size would be 245/45R18) at the front and 9.5'' 20 ET (tyre size would be 265/45R18) rear would this affect my speedometer from standard size of fronts 8'' 30 ET (tyre size would be 225/45R18) and rears 8.5 30 ET (tyre size would be 245/45R18),

 

Would this have any affect on the speedometer?

 

Thanks in advance

 

you will want 245/40/18 front and 265/40/18 rear on your new wheels