Larger tyres and diff damage in 80 series Landcruiser?

Joined
Dec 29, 2022
Messages
9
Location
Sydney.Australia
Hi folks

A few months back I got new tyres on my 1990 HZJ80R Landcruiser and wound up with 35" all terrains, as the shop said they couldn't source the 33" ones that I previously had. Yesterday a fellow Cruiser owner asked me if I was worried about the possible diff damage, as he had heard of instances of diffs being damaged and even broken by larger tyres. This is the first I had heard of this, and the shop certainly didn't flag it, although they may have just been interested in upsizing the sale... All they flagged was to be mindful of the difference on the speedo and odo.

All I've been able to find online is a generic article stating this:

"Everything that indirectly attaches to your tyres is put under more stress when you fit bigger tyres. This includes your CV’s, steering box, steering shafts, axles and differentials. Many people will not break components on standard tyres (especially CV’s) but as soon as they go up a few tyre sizes the breakages happen on a regular basis." (Fitting bigger tyres to your 4WD; what should you consider? - https://www.4wdingaustralia.com/4x4/fitting-bigger-tyres-to-your-4wd/)

Has anyone encountered or heard of this issue, or know of any other factors that might make such damage more likely (so that I can avoid or minimise those factors)? I'm pretty keen to not destroy any bits of my truck and well annoyed that the tyre shop didn't know or care to mention it :mad: I'm kinda tempted to go to another shop to swap back to 33s, cut the loss and try to sell the 35s if the risk is substantial.

Many thanks for any insight!
 
Joined
Dec 30, 2022
Messages
34
Location
Chico California
Bigger tires will stress the drivetrain more. Weather or not it causes a problem comes down to how you drive it.
Hammer down all the time, and you'll probably be breaking stuff. Drive like a normal person and you probably wont.
 
Joined
Mar 3, 2021
Messages
304
Location
bc
itll be fine it's a landcruiser, might make you a bit slower though
if it was a jeep with a dana 30 i'd be worried

What it does do is put you outside of the ideal gearing in your diffs.
If you wheel it hard and have a front locker i would suggest upgraded bifs and axle shafts (longfields, rcv etc)
 
Joined
Dec 29, 2022
Messages
9
Location
Sydney.Australia
itll be fine it's a landcruiser, might make you a bit slower though
if it was a jeep with a dana 30 i'd be worried

What it does do is put you outside of the ideal gearing in your diffs.
If you wheel it hard and have a front locker i would suggest upgraded bifs and axle shafts (longfields, rcv etc)
I've noticed it's a bit slower and also seems a bit underpowered when travelling at speed - harder to maintain speed uphill in particular. And yeah, the gears feel weird.
 
Joined
Jan 31, 2005
Messages
4,096
Location
Denver CO
You can break stuff with 33s too…search for threads on breaking the front diff when reversing under load. 80 series section will get you more results and responses.
 

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