Wheel size

[dnielsen]

Am in the process of upgrading vehicle. 
Current vehicle is Nissan Navara with 17' wheels
I have noticed that most new-ish 4WD now come with 18' wheels instead of 17". My understanding is that 18" tyres have a shorter sidewall in comparison to 17".
Does this make them more susceptible to side wall punctures or other damage?
Interested in peoples experiences and thoughts
Regards
Daryl

[Troopy_03]

Am in the process of upgrading vehicle. 
Current vehicle is Nissan Navara with 17' wheels
I have noticed that most new-ish 4WD now come with 18' wheels instead of 17". My understanding is that 18" tyres have a shorter sidewall in comparison to 17".
Does this make them more susceptible to side wall punctures or other damage?
Interested in peoples experiences and thoughts
Regards
Daryl

Scratch that, there are more 18" tyres around these days, but it depends if they'll fit under your guards without big mods and possibly speedo correction.

[Bird]

Scratch that, there are more 18" tyres around these days, but it depends if they'll fit under your guards without big mods and possibly speedo correction.

18s are also more $$ and can be harder to find in remote locations if thats what travelling you do.

[Mace]

And your more likely to do damage to the rims with a smaller sidewall in rough & rocky going...   

[lloydus67]

Size of the rim has little to do with sidewall damage and more to do with the sidewall size and Tyre ply rating.
For instance a 285 75 r18 will have more sidewall than a 265 75 R17
As the second number (75 in this case) is the percentage of the Tyre width (the first number) that relates to the sidewall height. If that makes sense.


Sent from me

[Troopy_03]

Size of the rim has little to do with sidewall damage and more to do with the sidewall size and Tyre ply rating.
For instance a 285 75 r18 will have more sidewall than a 265 75 R17
As the second number (75 in this case) is the percentage of the Tyre width (the first number) that relates to the sidewall height. If that makes sense.


Sent from me

Yeah but to get the tyre to fit in his guards, he will may have to go to a lower profile than a 75, which is where sidewall damage comes into it. The difference difference between a standard Navara 255/65/R17 and  285/75/R18 is 5" in diameter.. I don't have a Neesan, so I'm only guessing on what sort of clearance they have. I suppose it's only an inch difference, so maybe the same profile or a tad smaller..

Better off talking to a tyre supplier to get the good info on how available, and difference in price for odd sizes.

[lloydus67]

Lol I was just using easy numbers for comparison only. Just for an example of sidewall heights


Sent from me

[Bird]

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

[Troopy_03]

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

Speedo error calculator
https://tiresize.com/speedometer-calibration/

[NZMarkb]

Speedo error calculator
https://tiresize.com/speedometer-calibration/

The only issue with that is that speedo's aren't correct from factory (usually read 5% low)
Fitted 33's to my 200 now it's bang on 

[Troopy_03]

The only issue with that is that speedo's aren't correct from factory (usually read 5% low)
Fitted 33's to my 200 now it's bang on 

They might read 5% high, they aren't allowed to read low. ie when the speedo reads 100Kph, your actual speed is less than 100Kph. Which is why changing to bigger diameter tyres can make your speedo read too low, and make it illegal. What ADRs say is that you speedo can't read low, but can read up to 10% of actual + 4Kph over your actual speed

When your actual speed is 100Kph, your speedo can read anywhere from 100Kph to 114Kph.

When I changed to a different profile tyre on my Troopy, it changed my speedo reading so that the speedo is reading 100Kph, when I'm actually doing 99Kph, by the GPS. But because your needle is pretty thick, it's a bit iffy being so close.

[NZMarkb]

They might read 5% high, they aren't allowed to read low. ie when the speedo reads 100Kph, your actual speed is less than 100Kph. Which is why changing to bigger diameter tyres can make your speedo read too low, and make it illegal. What ADRs say is that you speedo can't read low, but can read up to 10% of actual + 4Kph over your actual speed

When your actual speed is 100Kph, your speedo can read anywhere from 100Kph to 114Kph.

When I changed to a different profile tyre on my Troopy, it changed my speedo reading so that the speedo is reading 100Kph, when I'm actually doing 99Kph, by the GPS. But because your needle is pretty thick, it's a bit iffy being so close.

Sorry you are correct they read higher than what you are actually doing

[Troopy_03]

Sorry you are correct they read higher than what you are actually doing

No probs mate, it is confusing sometimes for me.. But I blame old age.

[NZMarkb]

No probs mate, it is confusing sometimes for me.. But I blame old age.

😂😂 yeah I was having a senior moment 👍