tyre pressure

Talk about the E-Type Series 3

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fjafulton
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#1 tyre pressure

Post by fjafulton » Sun Oct 22, 2017 11:39 am

my series 3 keeps clipping the exhaust on anything even getting close to a bumpy road , and I have checked that the suspension is set up correctly.

Could i bit of extra pressure in the tyres as they do look a little under pressured at 28/30, but finding out the correct setting has proven very difficult, thinking of trying 32 / 35 to see how it works.

the tyres are riken 710 tyres 205/70 r15


they were not fitted by me and i probably should changed the tyres, but they are quite new.

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mgcjag
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#2 Re: tyre pressure

Post by mgcjag » Sun Oct 22, 2017 12:38 pm

Hi..welcom to the forum...whats your name...please try to put it in the signature area with your car year/ model....according to the S3 Jag manual there should be a measurement of 7.9in +- 0.25 between the bottom of the plate of the IRS to ground....check this first.....if low then you need to check bushes/springs..could aslo be you exhaust is hanging too low...i think you should be on 32 psi all round
Steve
1969 S2 2+2 & Building a C type replica

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malcolm
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#3 Re: tyre pressure

Post by malcolm » Mon Oct 23, 2017 8:37 am

I understand that a quite a few E's are around with the wrong exhaust hangers fitted, meaning they will ground. Worth checking.
Malcolm
I only fit in a 2+2, so got one!
1969 Series 2 2+2
2009 Jaguar XF-S

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42south
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#4 Re: tyre pressure

Post by 42south » Tue Oct 24, 2017 8:13 pm

hi
Definitely have a look at your mounting of the underbody mufflers and exhaust pipes. Make sure the mufflers are right up in the cavities. And check they are the same oval shape as the OEM mufflers, I'm assuming someone has replaced them at some stage.
The pipes where they go under the IRS should have a flattened upper surface to help the clearance, this means the mufflers rear lower edge will be higher.
These were the problems with my car, no probs now, and our roads are rough down here, I run the jag recommended pressures of 24 front and 28 rear. My tyres are 225/60/15 which are 1/2 an inch smaller diameter than yours
One other thing. do make sure the measurement under the IRS is correct as per the manual. I have got Konis on my car, with new springs, but still had to have alloy spacers made up to fit under the springs to bring the ride height up to spec.
Cheers
Mark Brown
1971 S3 Etype
Son: when I grow up, I want to be a pilot
Dad: You’ll have to choose.

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morganjag
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#5 Re: tyre pressure

Post by morganjag » Wed Nov 08, 2017 3:20 pm

I am getting rear tyre squeal if turning right on a rounderbout , wondering wether i should drop tyre pressure from figure in book , or maybe the tyres have hardened and are now usless for grip ?

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JJC
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#6 Re: tyre pressure

Post by JJC » Sat Nov 25, 2017 10:31 pm

One trick is to keep relatively fresh rubber O rings to hold up exhaust. Also, after replacing them, tie them up in the middle with a small tie wrap. Keeps them from slipping off, and gets you just a tinny bit more clearance. I use 215 /70/15 on my car for years...never a problem.

John

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dougal
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#7 Re: tyre pressure

Post by dougal » Wed Aug 08, 2018 8:56 am

Hi

I have put a few tyre pressure charts on here https://www.longstonetyres.co.uk/classi ... -type.html

click pressures on one of the tabs at the top.

I would be interested in any comments
Chain Gang for ever

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Heuer
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#8 Re: tyre pressure

Post by Heuer » Wed Aug 08, 2018 10:24 am

Are the Dunlop Aquajets the same as the Dunlop SP41's? If so the recommended pressures were 32/32psi - 40/40psi seems incredibly high. I realise Jaguar quoted two pressures, one up to 125mph and one to max speed, but for real world driving it would seem sensible to use the former in all cases.
Image


On my OTS with XVS tyres I have found, after much experimentation, that 30/35psi suits my driving style. This pushes the handling towards oversteer, but not dangerously so.
David Jones
S1 OTS OSB; S1 FHC ODB

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Simon P
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#9 Re: tyre pressure

Post by Simon P » Thu Aug 09, 2018 8:21 am

Agreed. I've got Aquajets on my S2 and 32 all round seems the best setting. I've tried higher but it doesn't seem to suit the car as well - can't imagine what it would be like at 40 all round therefore!
1969 S2 FHC - 1R20258
1993 Lancia Delta HF integrale Evo II

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malcolm
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#10 Re: tyre pressure

Post by malcolm » Thu Aug 09, 2018 8:36 am

Don't really understand why high speed motoring should demand higher pressures. At higher speeds, the tyres get hotter, so pressure increases. So why have them higher to start? Can anyone educate me?
Malcolm
I only fit in a 2+2, so got one!
1969 Series 2 2+2
2009 Jaguar XF-S

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Simon P
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#11 Re: tyre pressure

Post by Simon P » Thu Aug 09, 2018 12:34 pm

I'm struggling to get my head round how you get out at 125mph and pump in those extra 8psi ready for the onward charge to the vehicle's maximum!

:bigrin:
1969 S2 FHC - 1R20258
1993 Lancia Delta HF integrale Evo II

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Heuer
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#12 Re: tyre pressure

Post by Heuer » Thu Aug 09, 2018 1:22 pm

malcolm wrote:
Thu Aug 09, 2018 8:36 am
Don't really understand why high speed motoring should demand higher pressures. At higher speeds, the tyres get hotter, so pressure increases. So why have them higher to start? Can anyone educate me?
it was based on the fact that the E-Type was originally equipped with RS5 cross-ply tyres which squirm around at speed and so build heat very quickly. Increasing the pressure stiffened the tyres and reduced the squirming at the cost of ride comfort.

This was the reason Michelin launched the first radial tyres in 1956 specifically for the fast, straight Autoroute's, Autobahn's and Autostrada's of Europe. We were slow to adopt them in the UK because we did not have many motorways and most British cars continued to use cross ply tyres into the late 1960's.
David Jones
S1 OTS OSB; S1 FHC ODB

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malcolm
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#13 Re: tyre pressure

Post by malcolm » Thu Aug 09, 2018 1:24 pm

Thanks David, get it now.
Malcolm
I only fit in a 2+2, so got one!
1969 Series 2 2+2
2009 Jaguar XF-S

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