Tyre size

[Brenton]

My new legnum is running 225/45 on 17x7.5 rims. Rear tyres are close to needing replacing. Would it be safe to use 235/45 on rear or would the difference in circumference/diameter have adverse effects on transfer case and other driveline components?

 

[Dice]

235 is a fraction wide, 225 is recommended for 7.5" wide rims.

 

[Scradam]

Avoid different tyre circumferences at all costs. Your centre diff's viscous coupling will be working overtime to compensate for the difference in rotation speed and will get unnecessarily hot.

If you really need to go staggered:
Here are some combinations that are calculated to be approximately equal in rolling diameter. (within 0.3%)

• 235/40R18 & 265/35R18 & 235/45R17 & 265/40R17
• 225/40R18 & 255/35R18 & 225/45R17 & 255/40R17
• 215/40R18 & 245/35R18 & 215/45R17 & 245/40R17
• 205/40R18 & 235/35R18 & 205/45R17 & 235/40R17

But keep in mind that different manufacturers/models may vary in dimensions from specified.

 

[Brenton]

Think I'll be better just getting a pair of 225/45 for now and rotate when I change engine oil, full set of 235 when they're worn.

 

[Brenton]

Would a rolling diameter and height difference of 1.0% be acceptable?

 

[AKKO]

How many spare diff's do you have?

Type V will have slightly more tolerance iirc.

 

[Bourbonator]

so I cant run 245 on rear and 225 on front ? ive been told same tyre all the way round, can someone please verify this as ive fitted the 245 all ready :-O

 

[AKKO]

If you like looking at the AYC light on your dash dont let us stop you, but the diff might soon enough.

 

[Bourbonator]

Thanks im getting told 10 different things, I think it safe to say go all the same sizes

Cheers

 

[steveP]

Avoid different tyre circumferences at all costs. Your centre diff's viscous coupling will be working overtime to compensate for the difference in rotation speed and will get unnecessarily hot.

If you really need to go staggered:
Here are some combinations that are calculated to be approximately equal in rolling diameter. (within 0.3%)

• 235/40R18 & 265/35R18 & 235/45R17 & 265/40R17
• 225/40R18 & 255/35R18 & 225/45R17 & 255/40R17
• 215/40R18 & 245/35R18 & 215/45R17 & 245/40R17
• 205/40R18 & 235/35R18 & 205/45R17 & 235/40R17

But keep in mind that different manufacturers/models may vary in dimensions from specified.

I just saw this. I thought this myth was put to bed a few years ago. Many of us have been running staggered tyres with no problems.