Change 4 tyres at once?

tnegun

2013 Santa Fe front tyres are 70% and 40% tread left and the rear are on the wear limit as is the spare. OH had it at the tyre shop today to get a price and the shop wants to replace all 4 as its an AWD and the manufactures recommendation. I'm calling BS on it? Anyone know any different. I was going to 2 do now and 2 in June before we bring it to France and put the one with a bit of thread as the spare. Also 2 new on the rear?

colm_mcm

Just replace the ones that need replacing. You don’t have a proper full time 4wd system anyway.

Chippy01

A friend of mine posed the same question to me.
I had read somewhere that there is a limit built into various AWD systems as to how much of a difference in circumference and/or diameter of each tyre is permissable before possible drivetrain damage could occur.
For some reason the figure 3mm keeps popping into my braincells.
I would think that each manufacturer would have such info in the owners handbook.

I found the following online and sent him a message:-

""In an all-wheel-drive system, the central computer ensures that each wheel gets the right amount of torque.
It reduces slippage and maximizes the wheel control.
If any of the tyres have less tread amount or smaller circumference than the others, the computer will take incorrect readings and send wrong information to other components.
Driving with mismatched tyres can cause drivetrain damage.""

I believe that after much deliberation, he changed all the tyres.

Isambard

70% surely doesn't need replacing and 40% hardly does either surely.

Maybe replace the three worn out tyres, and move the 70% to the rear and the 40% to spare.

Toyotafanboi

You're already driving with 4 tyres at vastly different levels of wear and seeing no side effects so I dont see how fitting any amount of new tyres could make that worse.

That said, with 2 knackered tyres, one nearly knackered tyre and one ok tyre it'd be nice to fit a fresh set of 4 if you have the cash. Another option would be to fit 3x tyres the same brand as the 70% tyre and put the 70% on the O/S/R corner, it'd still be a nice setup and keep costs down a bit.

2 tyres certainly wont do any harm really on that car.

kirving

Chippy01 wrote: »

If any of the tyres have less tread amount or smaller circumference than the others, the computer will take incorrect readings and send wrong information to other components.
Driving with mismatched tyres can cause drivetrain damage."

I usually err on the side of caution with these things - but I'm not buying this one. The differentials and transfer case will handle any difference in rotational speed.

Front tyres on a front wheel drive car will wear much faster than the non driven wheels. This car only has an on-demand AWD system so by design will wear the fronts more quickly.

Even in permanent AWD systems, tyre wear won't be even necessarily due to torque split and cornering.

If a single tyre is significantly different to all the others, it may confuse the traction control system, but this would show as a yellow warning light almost immediately.

Cee-Jay-Cee

Just replace the two tyres for now. If your current tyres are 70% and 40% then that a difference of 30% so if you put on new tyres the difference will still be 30%. Put the new tyres on the front and the rotate them to the rear after 5k kms.

punisher5112

They say to fit new on rear

Isambard

could it be they want to sell tyres?

tnegun

Thanks for the comments guys, after the xmas can afford 2 now might stretch it another 4 weeks and go for all 4 keeping the one 70% as a spare. Have done some googling/reading and it doesn't seem to be set in stone that different wear levels are good or bad. Hyundai US seem to blame it on a lot of diff failures to get out of warranty work for example!