Disadvantages of running different tyres?

sweetie

My front tyres are getting changed soon to a different brand (michelin) and my back tyres (uniroyal rainsport) have a bit of running left on them so I'm going to leave them for a bit longer. Any potential issues with doing this?

Anjobe

It is better to keep a matched pair on each axle, but there is no problem having different tyres front and back. It would generally be advised to put the newer tyres on the rear though.

sweetie

Anjobe wrote:

It is better to keep a matched pair on each axle, but there is no problem having different tyres front and back. It would generally be advised to put the newer tyres on the rear though.

Thanks. Even for a front wheel drive?

Anjobe

Yes, its been discussed in other threads on the forum, but its basically a safety thing. If the front tyres have less grip then it will cause understeer if they let go, whereas if the rear tyres have less grip then that could lead to a spin. A spin is more dangerous as it is harder to control and more likely to lead to a serious accident.

sweetie

Anjobe wrote: »

Yes, its been discussed in other threads on the forum, but its basically a safety thing. If the front tyres have less grip then it will cause understeer if they let go, whereas if the rear tyres have less grip then that could lead to a spin. A spin is more dangerous as it is harder to control and more likely to lead to a serious accident.

Ah Ok cheers. So I should change the back tyres to the front and put the new ones on the back.

5W30

Anjobe wrote: »

Yes, its been discussed in other threads on the forum, but its basically a safety thing. If the front tyres have less grip then it will cause understeer if they let go, whereas if the rear tyres have less grip then that could lead to a spin. A spin is more dangerous as it is harder to control and more likely to lead to a serious accident.

Ideally you want to have even grip across all 4 wheels though so it makes sense to rotate wheels to have it wear evently.

I don't see any advantage of running 1.3 mm tyres on the front and 7 mm tyres on the back, especially for heavy braking.

yourpics

I have a practically new tyre on rear axle and the other rear tyre needs replacing, would there be any issues here? Should I try and source a very similiar tyre / tread pattern?

Jesus.

sweetie wrote: »

Ah Ok cheers. So I should change the back tyres to the front and put the new ones on the back.

Personally I'd do it the other way around if its a FWD

biko

yourpics wrote: »

I have a practically new tyre on rear axle and the other rear tyre needs replacing, would there be any issues here? Should I try and source a very similiar tyre / tread pattern?

Well, ideally you should change these in pairs but just get another new tyre and stick on.
As long as they are same size you'll be ok. If you can get same brand even better.

9935452

Jesus. wrote: »

Personally I'd do it the other way around if its a FWD

Agree there , sure doesnt the front axle do the most of the braking , the steering and accelerating .

CiniO

9935452 wrote: »

Agree there , sure doesnt the front axle do the most of the braking , the steering and accelerating .

It does, but without a good grip on rear axle, most people will not be able to keep car in the control during severe braking or steering which most likely will end up in bad accident.

My advice which I already presented here many times.
If you are well trained in advanced vehicle control and feel you can handle any unexpected oversteer vehicle behaviour and recover from side skid at any time, put better tyres on the front.
If you are not - put better ones on the back.

CIP4

CiniO wrote: »

It does, but without a good grip on rear axle, most people will not be able to keep car in the control during severe braking or steering which most likely will end up in bad accident.

My advice which I already presented here many times.
If you are well trained in advanced vehicle control and feel you can handle any unexpected oversteer vehicle behaviour and recover from side skid at any time, put better tyres on the front.
If you are not - put better ones on the back.

I'm not arguing with you as I agree with what your saying to an extent. By having the better tyres on the back your less lightly to loss the back of the car under heavy braking. But at the same time on a fwd your front tyres are putting out the power on the roads, steering and doing the vast majority of the stopping. So by having the good tyres at the back your not going to be able to stop the car as quickly so that could be the difference between hitting someone and not hitting them or hitting them at higher speed.

I personally always put the good tyres on the front with fwd cars and I've never had a major issue but then I would never have bad or bald tyres on a car. But you are right in the fact that you will loose the back quicker withy he bad tyres on it but I think a decent driver should be able to keep the car under severe breaking even while going around a corner for example.

beauf

Bad tyres on the front of a FWD means earlier understeer which is easier to regain control. Its intuitive. Also means you'll drive to the slower limit of your front tyres. Most people will be able to recover from this.

Bad tyres on the back of a FWD means earlier oversteer which is harder to regain control. Its not intuitive. It means you can drive beyond the limit of your rear tyres.

But driving on the limits, or emergency braking should be very rare. In normal driving the front tyres do most of the work. So they wear quicker.

Unless its a Clio V6. Which wears all the tyres equally.

cantdecide

My instinct is telling me that theoretically, better tyres at the back may have some advantages. Maybe if you have two good tyres and two bad tyres and you don't plan on replacing the bad ones any time soon then maybe there's a point. However, I don't see it making too much of a difference if you have two 3.5mm tyres and two 5.5mm tyres I think the grip levels may only become a factor in extreme cases.

All this is before considering understeer additional weight of the engine, braking and other factors.

Any tyre centres you go to will tell you to put better tyres on the front and okay, they may not necessarily be engineers themselves but if all the very clever people in the supply chain decided that rear tyres need priority, then the reasoning would filter down.

beauf

If you put the most worn tyres on the front, it will increase the difference in tread front and back quicker. I seem to remember the old advice used to be rotate the tyres to they wear evenly.

These days the advice seems to be put the best tyres on the back.

Of course better advice would be to ban cheap chinese ditch finders. make more of a difference perhaps.

CiniO

I have 1st hand experience which was the best lesson I could get.
Few years back I bought a car, which unfortunately came with rather poor quality budget tyres. Front ones were not too bad - rather higher range of budget.
Rear ones were absolute rubbish - probably lowest range of budget tyres.
I've driven a car, and it happen many times my rear broke away on rounadabouts, on sharp turns, etc. I didn't think much about it, as I'm quite experienced controlling skids, it was no problem for me. I was just aware rear tyres are cr@p.
However one day, when my wife was driving to work, she skidded on a bend, and ended up in the ditch writing the car off. Luckily she didn't write herself off - just the car.

Since then, I would always use reasonable quality tyres, and put better ones on the rear on cars my wife drives.

colm_mcm

I think the key thing is to not have rubbish tyres though.

CiniO

colm_mcm wrote: »

I think the key thing is to not have rubbish tyres though.

Yes, that surely helps, but even if I had best quality premium brand, but worse on rear and better on the front, my wife still could have crashed if speed was higher as rear would still break away.

If all 4 tyres were equally crap or front crapier than rear ones, she would most likely never have crashed.

The main reason the crash occured was because rear of the car skidded, and main reason the rear skidded was because rear tyres provided worse grip than front tyres. It was as simple as that.

beauf

That and not replacing them when they skidded on roundabouts.

Decent tyres do not do that unless there is a large discrepancy between front and back.

Normal wear on decent tyres shouldn't have you sliding on roundabouts in a fwd. Suspension also is a factor.

9935452

CiniO wrote: »

I have 1st hand experience which was the best lesson I could get.
Few years back I bought a car, which unfortunately came with rather poor quality budget tyres. Front ones were not too bad - rather higher range of budget.
Rear ones were absolute rubbish - probably lowest range of budget tyres.
I've driven a car, and it happen many times my rear broke away on rounadabouts, on sharp turns, etc. I didn't think much about it, as I'm quite experienced controlling skids, it was no problem for me. I was just aware rear tyres are cr@p.
However one day, when my wife was driving to work, she skidded on a bend, and ended up in the ditch writing the car off. Luckily she didn't write herself off - just the car.

Since then, I would always use reasonable quality tyres, and put better ones on the rear on cars my wife drives.

You had what we term ditch finders on the back of the car, even with good thread on a lot of cheaper tyres they just dont have grip. Great wear but no grip.
My latest car had a set of Dextero tyres on it , it could spin the wheels in the dry when you put the boot down in second gear , now on pirellis , it struggles to spin them now in the wet in first.

*Kol*

This is a THREAD, tyres have TREAD!!

yourpics

I would always put the better tyres on the front of a FWD, better grip for ice / snow / wet during the Winter.
As for heavy braking etc, just drive slower!! Saves fuel also!

biko

It may seem counter-productive gauging by the posts above but the new tyres goes in rear.

Tyres with deep tread are less likely to puncture and it can be more difficult to control a car with a damaged rear tyre as you don't feel it in the steering immediately.

Rear tyres provide stability, and without stability, steering or braking on a wet or even damp surface might cause a spin. If you have new tyres up front, they will easily disperse water while the half-worn rears will go surfing: The water will literally lift the worn rear tyres off the road.

In a wet country like Ireland this is a significant risk.

https://www.youtube.com/watch?v=gSz7cm6MwH0

colm_mcm

CiniO wrote: »

Yes, that surely helps, but even if I had best quality premium brand, but worse on rear and better on the front, my wife still could have crashed if speed was higher as rear would still break away.

If all 4 tyres were equally crap or front crapier than rear ones, she would most likely never have crashed.

The main reason the crash occured was because rear of the car skidded, and main reason the rear skidded was because rear tyres provided worse grip than front tyres. It was as simple as that.

I'm having difficulty following that tbh. You're saying the rear tyres didn't break free because they were lethal but because the front tyres were too grippy?

*Kol*

yourpics wrote: »

I would always put the better tyres on the front of a FWD, better grip for ice / snow / wet during the Winter.
As for heavy braking etc, just drive slower!! Saves fuel also!

Not much point having loads of grip on the front of the car when the back of it is coming around to meet you. The whole point is that you will sense a loss of grip quicker through the front wheels than the rear. It really applies more-so to wet conditions as breaking traction on ice/snow can be difficult to avoid on normal tyres.

beauf

biko wrote: »

It may seem counter-productive gauging by the posts above but the new tyres goes in rear.

Tyres with deep tread are less likely to puncture and it can be more difficult to control a car with a damaged rear tyre as you don't feel it in the steering immediately.

Rear tyres provide stability, and without stability, steering or braking on a wet or even damp surface might cause a spin. If you have new tyres up front, they will easily disperse water while the half-worn rears will go surfing: The water will literally lift the worn rear tyres off the road.

In a wet country like Ireland this is a significant risk.

https://www.youtube.com/watch?v=gSz7cm6MwH0

Not a great video. Why does the white car not understeer (or aquaplane) at all. The point was the white car should understeer, and the driver slow down. In fact both cars maintain the same speed and only the black car aquaplanes & oversteers. I dunno why they put a RWD BM in the middle if it either. It doesn't really show under-steering at all.

CiniO

colm_mcm wrote: »

I'm having difficulty following that tbh. You're saying the rear tyres didn't break free because they were lethal but because the front tyres were too grippy?

I put it in other words then.

In case I described rear tyres were much worse than front ones (provided much worse grip than front ones).

Obviously that was the reason they broke free.

But if front tyres were worse than they were - i.e. the same crap as rear ones or worse, then it would be impossible to go as fast through the bend, and therefore possiblity of rear tyres breaking free would be minimal.

The same - even if both sets were top spec premium brand tyres, but rear ones worse than front ones, still there is a chance of rear breaking free.
If front ones are worse than rear ones, then you can't achieve such speed on a bend to cause rear to break free.

beauf

CiniO wrote: »

I....then it would be impossible to go as fast through the bend, and therefore possiblity of rear tyres breaking free would be minimal.....

I think you mean impossible without coming off the road. If you go to fast into the corner, you simply won't be able to turn. Most of your braking is on the front. Which will have the worse grip. So while you might not spin. You still might crash.

https://www.youtube.com/watch?v=OKuhNM5Q9Mg