Tyre question

korky

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I'll soon be replacing my existing tyres and am looking at the Falken Euroall Season Van 11's. To up the load rating on the rears to 112 I will need their 225/70/15 size, up from my existing 215/70/15's.
Will this affect my gearing ratio much, or my speedo reading?
 
Will affect both, but I wouldnt think by too much.
Hard to say for sure though as I don’t know the vehicle

Tire Size Calculator

Free calculator to find the dimensions of a tire based on its code. It also helps in choosing alternative tire sizes based on rim size or comparing two tires.
www.calculator.net www.calculator.net
 
225 is the width and 70 is the % side wall depth to tread width , so the wider tyre would make a very slight difference to the recorded speed as the sidewall would be slightly bigger but in my opion not enough to worry about
 
korky said:
I'll soon be replacing my existing tyres and am looking at the Falken Euroall Season Van 11's. To up the load rating on the rears to 112 I will need their 225/70/15 size, up from my existing 215/70/15's.
Will this affect my gearing ratio much, or my speedo reading?
Click to expand...
No thats the width not hight, but do watch they dont foul springs etc or inner gaurds or full lock.
 
How to Read Tire Markings
  • 215/225: The tire width in millimeters from sidewall to sidewall.
  • 70: The aspect ratio (sidewall height). This is the height of the tire expressed as a percentage of the width.
  • 15: The wheel or rim diameter measured in inches
Tire width has increased from 215 to 225 mm i.e. 10mm (under 1/2 inch)
Tire height has increase from 70% of 215 mm to 70% of 225mm which is 7mm (under 1/3 inch).
The increase in tire height increases the diameter of the wheel & thus the circumference.
This means that one revolution of the wheel will take the MoHo further than the speedometer & the odometer think it has gone.
i.e. the speedometer & the odometer will give low readings.

I'm not going to show the calculation because for those who know it is trivial, and for those who don't it looks complex, but the under reading will be just over 1.3%.

i,e, when you are travelling at 50mph the speedo will show just over 49mph.
When you travel 1,000 files the odometer will show over 9988,
Instead of revving at 4,000 rpm at a given speed the engine will be at over 3,950 rpm

Management summary - the impact of upsizing the tyres of speedometer / odometer is not worth worrying about.

A word to the wise the - increase in tyre width may result in tyres contacting body work or chassis.
I used to be involved in 4x4 off road motor sport and saw a lot of over sized tyres damaged by steering stops.
Adjustment would have taken under 5 minutes but some people will not listen.
 
mark61 said:
Will affect both, but I wouldnt think by too much.
Hard to say for sure though as I don’t know the vehicle

Tire Size Calculator

Free calculator to find the dimensions of a tire based on its code. It also helps in choosing alternative tire sizes based on rim size or comparing two tires.
www.calculator.net www.calculator.net
Click to expand...
Ducato X250 PVC, light chassis.
 
I switched from 195 to 225 many years ago. This made a huge difference. Significantly better handling and slightly lower engine speed.
Yes, the speedometer does read slightly low, so I fitted a GPS HUD speedometer. Don't get an ODB one, because that will read wrong.
Interestingly, that was delivered reading between 6% and 7% high, but I found the setting to make it show the actual speed.
The only complication is that the odometer reads low and any mpg figures are wrong, but I have a calculator.
 
Finally got the Falken's fitted in 225 up from 215. Initial impressions are good. Much improved ride from the several sets of Hankook Vantra's I've been through since the original (2013) Conti Campers wore out. The Conti's were an awful ride.Thanks for the input folks, which gave me the confidence to change tyre size slightly.
 
Geek said:
I switched from 195 to 225 many years ago. This made a huge difference. Significantly better handling and slightly lower engine speed.
Yes, the speedometer does read slightly low, so I fitted a GPS HUD speedometer. Don't get an ODB one, because that will read wrong.
Interestingly, that was delivered reading between 6% and 7% high, but I found the setting to make it show the actual speed.
The only complication is that the odometer reads low and any mpg figures are wrong, but I have a calculator.
Click to expand...
Thats width not hight so should make no differance to speedo.
 
I could not get the falkens a few months ago and options are thin on the ground for 15 inch.
I now have Maxxis 4 season @£80 plus vat I was not complaining..
They replaced the contis that @ 5 years old were cracking in the center of the tread...
 
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