Tyre aging

[sanzomat]

Just thought I'd seek peoples opinions regarding tyres losing grip with age.

After de-immobilising the GTM I took her out for a quick spin and nearly did (twice). To be fair the road was quite greasy and I've not really got used to driving a lightweight rear wheel drive car. My last RWD was a MKIV Cortina that I sold back in 1989. I remember having fun power sliding the rear on that (in the days when power meant about 70hp - bog standard 2.0 pinto). The GTM seems to be quite keen to step out of line at the rear on relatively light throttle changes and the traction pulling away isn't as good as I'd hoped with the weight mostly on the driven wheels. Now I'm more aware its likely to happen I'm ready to lift off and opposite lock and starting to think it could be quite fun to enjoy some fairly low speed sliding. This is with a 1.6 so I'm thinking the 1.8 VVC must be quite a handful though.

I'm thinking about the tyres. They are Goodyear Eagle F1, 205/45/16 all around with loads of tread (at least 6mm). I've always thought of those as quite good tyres. Checking the date codes it seems they must have been with the car its whole life as the car was registered May 2004 and the tyres are all coded around week 40 of 2003. The wear seems to be even on all 5 (the spare is on a matching alloy). Seems hard to believe that even with swapping them around that 15,000 miles could be done on just 2mm of tread wear. Although the car spent the first 9.5 of its 10.5 years with a 1.4 single cam single point injection engine so maybe wasn't driven very hard.

I've checked the tyres and they have no obvious visible signs of wear, no cracks or suchlike, in fact look like new. I'm advised she's always been garaged so no overdose on sunlight or extremes of temperature.

So, I'm wondering whether purely their 11 years of age would have made them hard and slippery. If so, how deep would the hardness go? Would a few doughnuts scrub enough hard rubber off to reveal something softer and grippier underneath? Maybe I should just ditch them and get a set of R888s but it somehow offends me to waste so much treadwear depth. If I knew for sure that they have gone off it would make it an easier decision but a nagging concern says what if its no different with new rubber...

[paintman]

Had the same trouble with the Hood, so after failing to catch it one day coming off a roundabout and spinning on to the grass verge backwards decided on getting new softer rubber (Toyo T1R's) .

They certainly did the trick but are wearing out much quicker.....but they feel a lot safer!!

     Tony

[benchmark51]

I went to T1r's and find them fine, but I have had my geometry done at Track developments as well. Might pay you to go there first, see what Dave says. Perhaps the goodyears are better suited to shopping trips.

[Iancider]

The tyres do sound old and they can harden with age.  I visually judge it by the side of the tread-blocks - if they look shiny it is a sign of oxidation which hardens or platicises the rubber. We seem particulalrly good in the kit-car world at building cars and not using them so the tyres can reach their age limit before they are worn out.  My rule of thumb is that about eight years seems to be the absolute limit even for a good tyre (5 is recommended).  Look for a very dull sidewall with cracks as a sign of age - usually fatal at the point.  You are right that over-winter oxidation can be scrubbed off on a dry road with a few "donuts" or the like but not if they are too far gone.

Also you have low profile tyres - 45 ratio and they are not good for handling anyway.  Like Benchmark I run T1R's 55 profile as general purpose tyres but even they are a little skittish in the wet.  They have pretty firm tyre-walls but not nearly as firm as 45's would be.  My race tyres are now 888's and a 65 profile on 13 inch wheels for about the same rolling diameter and they are superb on the road but look like doughnuts on the car.  I have to runs the T1r's near 20 psi to get full flat road contact but the 888's will behave well down to about 17 psi on the road and possibly lower for the track.  There is a good link here:
http://www.profiletyres.co.uk/tyreAgeing.html

There is good tyre age advice from the Honest John website: http://www.honestjohn.co.uk/faq/tyre-age/

888's are not all-year tyres be warned.  They are not meant for very wet roads and should not be driven near freezing because they will crack.  My T1r's are okay but I cannot run them soft due to the harder tyrewall but I do run the rears a little softer to prevent the rear kicking out.

Regards
Ian

[Camber Dave]

At the very least reduce the damper rates so the car moves on its springs. This will allow the tyre to find grip and give you more time to feel what the car is doing.

On my van I change over to winter pattern tyres. 155/80 winter pattern/compound instead of 165/70 and the difference is notable even on a muddy surface.

On my MX 5 I have new tyres but also reduced the spring rates and raised the car off the deck. It is much more forgiving and has become a winter runaround. Previously I set it up like my track day customers, weight allowed for. (I select springs based on the frequency of the sprung mass - how bouncy it is!) In this configuration it rewarded pushing hard but only on dry roads. It was a bit squirrel-y on wet roads and likely to be unusable on Mud/snow....

There is a long thread on the locost forum on kitcars and tyres.

['The Gaffer']

What tyre pressures do you have? Sometimes people with new kit cars use same pressure as normal road cars which is way too high and will cause lack of grip etc.

Agreed, let Dave set the car up for you as well.

[Moleman]

I use 888's all year round & get Dave to set my car up each year which I wouldn't do without now. 

[Facial Hair Optional]

So, I'm wondering whether purely their 11 years of age would have made them hard and slippery. If so, how deep would the hardness go? Would a few doughnuts scrub enough hard rubber off to reveal something softer and grippier underneath? Maybe I should just ditch them and get a set of R888s but it somehow offends me to waste so much treadwear depth. If I knew for sure that they have gone off it would make it an easier decision but a nagging concern says what if its no different with new rubber...

It will be different with new Toyos trust me!! 11 year old tyres are potentially dangerous to your health and your car's wellbeing, they are simply not designed to last that long!  It seems almost everyone is using 888s these days, can they all be wrong?

[Facial Hair Optional]

What tyre pressures do you have? Sometimes people with new kit cars use same pressure as normal road cars which is way too high and will cause lack of grip etc.

Agreed, let Dave set the car up for you as well.

Very true, My Tiger had 32 psi in the rear and 35psi in the front when I got it, I nearly died of shock! I then ran them at 18 both front and rear but dropped the rear to 16 to help keep the back end in line, it worked a treat.

[Facial Hair Optional]

The tyres do sound old and they can harden with age.  I visually judge it by the side of the tread-blocks - if they look shiny it is a sign of oxidation which hardens or platicises the rubber. We seem particulalrly good in the kit-car world at building cars and not using them so the tyres can reach their age limit before they are worn out.  My rule of thumb is that about eight years seems to be the absolute limit even for a good tyre (5 is recommended).  Look for a very dull sidewall with cracks as a sign of age - usually fatal at the point.  You are right that over-winter oxidation can be scrubbed off on a dry road with a few "donuts" or the like but not if they are too far gone.

Also you have low profile tyres - 45 ratio and they are not good for handling anyway.  Like Benchmark I run T1R's 55 profile as general purpose tyres but even they are a little skittish in the wet.  They have pretty firm tyre-walls but not nearly as firm as 45's would be.  My race tyres are now 888's and a 65 profile on 13 inch wheels for about the same rolling diameter and they are superb on the road but look like doughnuts on the car.  I have to runs the T1r's near 20 psi to get full flat road contact but the 888's will behave well down to about 17 psi on the road and possibly lower for the track.  There is a good link here:
http://www.profiletyres.co.uk/tyreAgeing.html

There is good tyre age advice from the Honest John website: http://www.honestjohn.co.uk/faq/tyre-age/

888's are not all-year tyres be warned.  They are not meant for very wet roads and should not be driven near freezing because they will crack.  My T1r's are okay but I cannot run them soft due to the harder tyrewall but I do run the rears a little softer to prevent the rear kicking out.

Regards
Ian

Could not agree more Ian. I run T1Rs on my Cossie Fury and cant really go out on even a moist road! The car is still running a track suspension set up though and is a right flipping handful, so next Spring it'll be 888s and a trip to Dave G at Track Developments for sure even though the T1Rs have less than 500 miles on them (they came brand new with the car a few months back) I'll store them for the winter maybe and get Dave to set up the car for them for the off season perhaps??

One thing worth noting though is that cars/tyres/windscreen rubbers etc all seem to deteriorate faster when a car is not used! Leave a car to strand for a year or two and it'll rot into a heap it seems!! I've even read that if you are taking the car off the road over winter to remove the wheels or get the tyres off the floor and drop the tyre pressures to half to help preserve the rubber. Urban myth or wise words anyone???

[benchmark51]

I remember back in the late 70's, the lotuses on our forecourt would all suffer noisey wheelbearings if stood for very long.

[benchmark51]

Very true, My Tiger had 32 psi in the rear and 35psi in the front when I got it, I nearly died of shock! I then ran them at 18 both front and rear but dropped the rear to 16 to help keep the back end in line, it worked a treat.
[/quote]

I ran ratbag on oldish yoko's at 30psi, scary or what! The toyo's at 18psi are good. I find T1r's good at dumping water under my right armpit though!!

['The Gaffer']

I know from others experiences that leaving tyres in one place over the winter will result in flat spots. Always move the car a metre or so every week to prevent these flat spots. Bit off topic but valuable information.

[sanzomat]

Thanks everyone for some great advice.
I've just checked the pressures on the side that is accessible whilst in the garage and both front and rear are at 32psi. Based on what has been said here and having now read similar threads on other forums it looks like this may be a significant part of the problem. The GTM Owners Club forum consensus seems to be that 24 rear and 22 front on Libras and Spyders is about right but all the 7 type drivers on the web are going around the 18 mark. I suppose that at 780kg the Spyder is a bit heavier than most 7's and also more is on the rear so maybe 24 is right. I'll try that first and maybe let a bit more out to see what happens.
I'll roll her out of the garage on Saturday and check how many clicks the rear dampers are on. I tried bouncing the back and if I put all my weight on the back it does drop about 1/2" but no bounce on the dampers. I might slacken off the spring preload a bit too.
It seems that most Libra/Spyder drivers on GTMOC are running the goodyear Eagle F1's and that seems to be what GTM used to recommend (and supply the factory built cars with) so based on the average mileage most people won't have worn them out yet. It may be just a matter of getting the pressures right and then I can use a bit more of the tread up whilst I'm learning the car and maybe go for some new rubber in the spring.

[benchmark51]

When I first set mine up, it was guesswork. I noticed a lot suspension travel and the front wheels were visibily toeing in and out as it bounced, tyre wear not good either. So I counted the available clicks on the dampers, had 20. So set them all to mid position, that stopped the toe in/out as a lot of the bounce was gone(as was the ruddy squeeking). Took the tyre pressures from 30 to 18psi. That improved things a lot. When I had camber dave check it he set ride heights, all angles and weights. With me in it, full tank, bag o tools, cans of fuel/water it came in at 638kg. I did find the rears a bit hard on me bum so softened it just a bit and now it's quite comfy and handles quite well. After 3000 miles, tyre wear is even and slight. I don't do track days, I'm happy to aggravate straightlineshirleys in beemers!

[sanzomat]

http://www.demon-tweeks.co.uk/motorsport/tyre-treatments/demon-tweeks-grip-tyre-softener

Anyone used this stuff? Someone on GTMOC suggested it might be worth a try, even if just to check whether I'd see a difference with new rubber before ditching the remains of the goodyears.

Having googled it there seems to be mixed opinions (like everything in life!). It seems to be banned by the MSA though so must make some kind of difference. The smell seems to be an issue though. One post suggested it attracts women. Well, the actual quote (apparently from an aussie) was that it attracts women like dingos, but who wants a woman like a dingo.

Anyway, I've now dropped the pressures down to something more reasonable (23 rear/21 front) but didn't have time to drive it. The contact patch looks bigger but they don't look under-inflated at all. The dampers were already only on three clicks so I've left them like that. Lets see what it feels like tomorrow with a santa hat on...

[Moleman]

I've never seen this before. Looks good if it does work?

[benchmark51]

At £70 a gallon + vat! . Do you get a scantily clad to apply it?