Tyre issue

[ZX9er]

Hi all,

I was wondering if anyone has had any experience in using 235x40x18 instead of the recommended 245x40x18, my car is a XR6 BA with the factory 18's of the day

I got a puncture the other day and the tyre repair place is suggesting I use 235 mainly due to cost.

[MOTIV8]

Originally Posted by ZX9er

Hi all,

I was wondering if anyone has had any experience in using 235x40x18 instead of the recommended 245x40x18, my car is a XR6 BA with the factory 18's of the day

I got a puncture the other day and the tyre repair place is suggesting I use 235 mainly due to cost.

By changing the size of your tyres it may throw out the speedo slightly due to a different rolling circumference........ Try the following link to give you an idea of how much difference there may or may not be

Tyre Calculator

[GRNKPR]

Originally Posted by ZX9er

Hi all,

I was wondering if anyone has had any experience in using 235x40x18 instead of the recommended 245x40x18, my car is a XR6 BA with the factory 18's of the day

I got a puncture the other day and the tyre repair place is suggesting I use 235 mainly due to cost.

should be ok wont affect speedo if any ,its only width

[F6 R-Spec]

The hight of a 235/40/18 to a 245/40/18 is diffrent, the profile is worked out on the width of the tyre.

The 40 bit means the % of the width of the tyre is the hight. make sense?

[ZX9er]

Originally Posted by MOTIV8

By changing the size of your tyres it may throw out the speedo slightly due to a different rolling circumference........ Try the following link to give you an idea of how much difference there may or may not be

Tyre Calculator

Thanks for the reply I will check it out.

[ZX9er]

Originally Posted by TL6B2

The hight of a 235/40/18 to a 245/40/18 is diffrent, the profile is worked out on the width of the tyre.

The 40 bit means the % of the width of the tyre is the hight. make sense?

Thats true and yes it makes sence... i decided to stick with the original size. The cost difference between 235's and 245's is anything up to $100 for the same tyre.

Cheers ppl

[Geoff EL 4.0]

Originally Posted by TL6B2

The hight of a 235/40/18 to a 245/40/18 is diffrent, the profile is worked out on the width of the tyre.

The 40 bit means the % of the width of the tyre is the hight. make sense?

No mate thats all wrong.
245/40/18 means
245=24.5cm Width
40=4cm Profile(top of rim to top of tyre)
18=Well we all know that means Inch

[Geoff EL 4.0]

Originally Posted by MOTIV8

By changing the size of your tyres it may throw out the speedo slightly due to a different rolling circumference........ Try the following link to give you an idea of how much difference there may or may not be

Tyre Calculator

Just like grnkpr said it wont change the circumference the middle number is what you want to look out for 245/>>>>40<<<</18 if that and the inch doesnt change(the 18) then your speedo is alrite. the only thing that is bad will be your grip issue but that all depends on the tyres rating and that a whole different story that im not going to explain without anyone wanting it.

I know what im talking about ive been a tyre fitter for over 6 months and i even knew these things before i was one.

[nb_351]

sorry mate but your wrong...
im a mechanic and a tyre fitter aswell, even before i was i knew all about it... reading magazines and the like, talking to my dad and people in the trade...
by your meaning, if i had a 235/40/18 its the same rolling diameter as something like a 295/40/18...
its not...
either a lot of people are wrong and your right, or the way ive been taught is correct...
sorry to shoot you down, but people can be dangerous with the wrong knowledge...
and yes zx9er, your speedo will be over slightly, not by much though...
the tyre is slightly smaller in diameter, so it will roll more times in the same distance than the original tyre, therefore telling the car its going faster than it really is...
the griup difference between a tyre thats 235 and a 245 will be miniscule if the tyre is the same design... the only thing that will also change is the load/speed rating... but again only slightly...

[Geoff EL 4.0]

Originally Posted by nb_351

sorry mate but your wrong...
im a mechanic and a tyre fitter aswell, even before i was i knew all about it... reading magazines and the like, talking to my dad and people in the trade...
by your meaning, if i had a 235/40/18 its the same rolling diameter as something like a 295/40/18...
its not...
either a lot of people are wrong and your right, or the way ive been taught is correct...
sorry to shoot you down, but people can be dangerous with the wrong knowledge...
and yes zx9er, your speedo will be over slightly, not by much though...
the tyre is slightly smaller in diameter, so it will roll more times in the same distance than the original tyre, therefore telling the car its going faster than it really is...
the griup difference between a tyre thats 235 and a 245 will be miniscule if the tyre is the same design... the only thing that will also change is the load/speed rating... but again only slightly...

Sorry mate i just checked with my step dad and he said the same thing as you. Very Sorry about this,but what can i say its what ive been told by many people and its just what ive come to believe. Once again sorry and now i know what it really is and will tell the people that fed me the wrong information.

[nb_351]

no need to apologise to me mate, the people who told you should be apologising...
i just cant let people carry on incorrect information... dont take it the wrong way or anything...
youll probably have trouble convincing them lol
the less people there are out there with the wrong info the better it makes our trade, which needs all the help it needs...

[ZX9er]

Thanks again all

Cheers