Inner tyre wear problem on a ISF

[BTCC_ Racer]

Hi all,

Was shocked to discover that my front inner tyres are down to cords -  the tyres themselves have over 3mm of life remaining.

Back in April changed the front lower arm bush to GSF ones and alround i put on Bilstien B6 (oem replacement shocks) at this point I had the geo checked and adjusted, the toe was hardly out but had it brought to zero on a Hunter machine.

I run 36 psi (cold) all around. Tyres are Michelin PS4s all round.

Car drives straight and since the bushes were fitted the steering response has improved , also when I had the shocks and geo done I didn't notice any tyre wear that not to say it wasn't there.

 

Thanks

[NemesisUK]

Increased camber would give increased tyre wear on the inner shoulders. Was that checked?

[hockeyedwards]

If it's both, definitely a set-up problem, maybe someone did an oopsie checking the alignment? Without pointing fingers, just a query, can you mess up the bush fitting enough for there to cause this sort of problem?

[BTCC_ Racer]

camber was:

Left 1.30 degree and right 1.32 I understand this cant be adjusted?

Toe was before adjustment 0.05 left and 0.08 right (the right was in the red)

Toes both adjusted to exactly zero.

[BTCC_ Racer]

2 minutes ago, hockeyedwards said:

If it's both, definitely a set-up problem, maybe someone did an oopsie checking the alignment? Without pointing fingers, just a query, can you mess up the bush fitting enough for there to cause this sort of problem?

Im not sure if you can mess up on a hunter machine, ive been going there for years never had a problem.

Maybe I didn't let the new shock settle enough? I picked the car up at 3pm (shocks fitted) left car parked for a day then went for a 20 min drive to alignment shop? I will say the cars ride height might have dropped a touch as the new shock settled? maybe this is a factor?

[hockeyedwards]

Something definitely doesn't quite add up for sure. Could it have happened before you changed everything, been unnoticed because it wasn't quite to the cords and then regular driving has pushed it over the edge?

Why did you change the bushes, were they knackered?

[Linas.P]

3mm that is pretty much end of life for the tyre anyway, even if it is extremely evenly worn there would not be much left in it. So let's say 1mm is acceptable difference on the 75% of the tyre - additional 2mm on the edges, so it would be acceptable that tyre with 3mm across 75% would be completely bald on the edge. Worn to cords is rather excessive... but I guess what I am saying - you looking at relatively minor issue here. If it would be 6mm tyre and inside bald then it would be big deal. 

As for wear on the front, it may not be issue with suspension alignment, for example I have noticed excessive wear in the front inner edge due to speed humps (as I tend to straddle them). Now sure IS-F is not IS250, but same principles for alignment and tyre wear apply. Perhaps firmer suspension and bushings transferred wear onto the tyres? 

[BTCC_ Racer]

4 minutes ago, hockeyedwards said:

Something definitely doesn't quite add up for sure. Could it have happened before you changed everything, been unnoticed because it wasn't quite to the cords and then regular driving has pushed it over the edge?

Why did you change the bushes, were they knackered?

its a fair assessment that I may not have noticed it as the wear might not have been much, I dont drive my car much as I have another two cars. The old ones looks o.k when on the car but once out they had some light cracking in them underload of a metal bar so in essence yes they were worn as they will flex under hard braking. 

I did feel a improvement in the steering, then again that could have also been the new shocks, again old ones weren't leaking but as they have done a 100k I just wanted to refresh some components as i went along. I tend to do this in all my cars slowly refresh them and bring them up to factory tolerances as possible. The new shocks have a much more controlled rebound over wavey roads, im not sure if the mileage on my stocks ones had seen them past the best my guess 100k and 14 year old probably yes.

[BTCC_ Racer]

10 minutes ago, Linas.P said:

3mm that is pretty much end of life for the tyre anyway, even if it is extremely evenly worn there would not be much left in it. So let's say 1mm is acceptable difference on the 75% of the tyre - additional 2mm on the edges, so it would be acceptable that tyre with 3mm across 75% would be completely bald on the edge. Worn to cords is rather excessive... but I guess what I am saying - you looking at relatively minor issue here. If it would be 6mm tyre and inside bald then it would be big deal. 

As for wear on the front, it may not be issue with suspension alignment, for example I have noticed excessive wear in the front inner edge due to speed humps (as I tend to straddle them). Now sure IS-F is not IS250, but same principles for alignment and tyre wear apply. Perhaps firmer suspension and bushings transferred wear onto the tyres? 

I'll measure the fronts shortly when i'm back at home but some good points you have mentioned.

I think i'm happy to accept that I didn't check nor measure the inside of the tyre edge before the new shocks and bushes and geo. I've ordered at set of PS4s they are arriving at the tyre centre tomorrow soon as they are fitted i'll get the pressure to 36 (I have my own gauge to check) and i'll get them to set the toe to 0. But the reading before will be crucial if its out then its an alignment issue, which could be down to the suspension settling or hitting a pot or two hole I cant recall hitting a huge pot hole.

 

 

[Linas.P]

2 minutes ago, BTCC_ Racer said:

I'll measure the fronts shortly when i'm back at home but some good points you have mentioned.

I think i'm happy to accept that I didn't check nor measure the inside of the tyre edge before the new shocks and bushes and geo. I've ordered at set of PS4s they are arriving at the tyre centre tomorrow soon as they are fitted i'll get the pressure to 36 (I have my own gauge to check) and i'll get them to set the toe to 0. But the reading before will be crucial if its out then its an alignment issue, which could be down to the suspension settling or hitting a pot or two hole I cant recall hitting a huge pot hole.

Actually, one more theory... which supports the theory that they were already worn just went unnoticed. 

If old bushing were indeed past their best, then specifically in IS and even more IS-F they are known to allow wheels to toe-out under braking, and toe-out is what results in inner edge wear. So this just supports idea that old bushings were allowing this to happen over-time and your front tyres already had excessive wear on inner edge before you even sorted out suspension. Whereas cords got exposed recently just as the tyre continued to wear. 

I would as well advise 4 wheel alignment as soon as new tyres are fitted. This is the best time to do alignment, as tyre wear contributes to alignment as well, so by doing it on new tyres you would give them best chance to wear evenly going forward. 

[BTCC_ Racer]

2 minutes ago, Linas.P said:

Actually, one more theory... which supports the theory that they were already worn just went unnoticed. 

If old bushing were indeed past their best, then specifically in IS and even more IS-F they are known to allow wheels to toe-out under braking, and toe-out is what results in inner edge wear. So this just supports idea that old bushings were allowing this to happen over-time and your front tyres already had excessive wear on inner edge before you even sorted out suspension. Whereas cords got exposed recently just as the tyre continued to wear. 

I would as well advise 4 wheel alignment as soon as new tyres are fitted. This is the best time to do alignment, as tyre wear contributes to alignment as well, so by doing it on new tyres you would give them best chance to wear evenly going forward. 

 

Can the rears be adjusted? Mine were o.k If so where are the adjustment points? 

totally agree with you, i'll get this sorted tomorrow, Im off to London next week I wasnt going to take the ISF but i might do to put some miles on the car.

[Linas.P]

55 minutes ago, BTCC_ Racer said:

Can the rears be adjusted? Mine were o.k If so where are the adjustment points? 

totally agree with you, i'll get this sorted tomorrow, Im off to London next week I wasnt going to take the ISF but i might do to put some miles on the car.

I believe there are no dedicated or very limited adjustment in the rear (not sure if IS-F had 1 dimension of adjustment), but the reason why 4 wheel "adjustment" is needed is  that front wheel alignment impacts the rear. So as far as I can remember it being done on my car - it is sort of backwards and forwards process, they adjust the front to be as close to spec as possible, check the rear and then dial the front back, repeated that few times until all 4 wheels where within "green" and that was best possible alignment.

So in principle rear wheels can't be adjusted or there is limited adjustment, but all 4 needs to be monitored during the process. The difference is that if you book for 2-wheels adjustment, they won't even measure what happens on the rear and front adjustment can impact it. At least that is my understanding.

Finally, I believe there are upgrades available which allows for some adjustment in the rear. But this is going into mods territory. 

[BTCC_ Racer]

1 hour ago, Linas.P said:

I believe there are no dedicated or very limited adjustment in the rear (not sure if IS-F had 1 dimension of adjustment), but the reason why 4 wheel "adjustment" is needed is  that front wheel alignment impacts the rear. So as far as I can remember it being done on my car - it is sort of backwards and forwards process, they adjust the front to be as close to spec as possible, check the rear and then dial the front back, repeated that few times until all 4 wheels where within "green" and that was best possible alignment.

So in principle rear wheels can't be adjusted or there is limited adjustment, but all 4 needs to be monitored during the process. The difference is that if you book for 2-wheels adjustment, they won't even measure what happens on the rear and front adjustment can impact it. At least that is my understanding.

Finally, I believe there are upgrades available which allows for some adjustment in the rear. But this is going into mods territory. 

I get you, with the hunter machine all 4 wheels are hooked up.

 

I run the stock 36 psi pressures - any suggestion if going higher is better?

[4969_LXS]

If it's any help, when I had the GSF bushes on put on mine. The inner edge was already worn due to the old bushes being past their best, the movement under braking and slow speed manoeuvring was quite noticeable. This LED to the inner edge wearing on my front left. It had worn down a lot after being on the car for 6 months and not many miles. Since swapping the bushes in April. The same tyre is still on the car and the front right has no uneven inner wear. so it looks to have solved the fast degradation rate on mine. Still on the original MY08 suspension. 

I suppose it doesn't help having around 54% of the cars weight up front on 225 tyres speaking OEM terms. Wider tyres spread weight over a greater area, might help a little but @Linas.P is right, it's usually toe that kills inner edges. 

Pressure wise I run 32psi all round cold. I did try the factory pressure settings for top speed once just to see. Never again 🤣

[BTCC_ Racer]

Little update, new tyres fitted. Front left toe was 0.04 and right was 0.02  Both were in the green zone.

Geo set to 0.00 toe both left and right, all boxes camber caster were in the green. The rear was also fine (i recently changed the rear tyres and the wear was even on the old set).

I'll take monthly measurements across the tyres to monitor the wear.

 

[CADman]

I had the same experience a couple of years ago needed to change the front tyres even though the rest of the tyre had plenty of meat the inner edge was showing canvas the front end would also tramline and the steering was vague. So did some digging on the web and found out the inner lower track control arm bushes are rubbish and have alot of give from new so when old and worn give you less control and alot of play. My solution was a pair of replacement polyurathene bushes with aluminium carriers from Figs Engineering in the US these cost just over £300 a pair but if you have access to a press you can get the bushes alone for £160 and press the bushes into the original carriers. To me this is a good fix because I now get even tyre wear across the tread so I no longer have to junk a good pair of front tyres with inner edge wear and I think this has saved me money long term, a big bonus is the steering fell is so much better the car tracks arrow straight over uneven surfaces and the car reacts to the smallest of inputs through the steering wheel, hope this helps.

[4969_LXS]

I noticed from doing a post blast check that the bushes get quite warm, especially if you've been having fun. The CATs are not far away from the LCA bushes. Might be causing the rubber to heat cycle fatigue a bit quicker than normal.

[CADman]

I had an IS250 before the ISF and this had the  same vague steering feel and would tramline, I think Lexus must use a softer bush to help with the 'Lexus ride quality' which degrades after time. I cannot stress how different the steering feel and straight line stabilty is since my upgrade. I have looked at my service sheet the tyres treads were checked and the fronts show half a mill difference from inner/middle/outer so thats a bonus to.

[BTCC_ Racer]

Ive changed the front trailing arm bushes to GSF ones which improved the steering feel.

Anyone have the part number for the lower inner arm bush? I rather use genuine Lexus ones, ideally GSF ones if they fit?

So far ive not had inner tyre wear but ive not been driving the car much so hard to tell.