Tyre Pressures

[Andy&Karen]

My TR4 is equipped with 72 spoke wheels shod with Rallye 580 Uniroyal Rain Tyres (Tubeless) 185/65 R14 88T. As I understand this to be non-standard to the TR4 can anyone say what would be the correct or suitable tyre pressures. Also, whilst I await delivery of the workshop manual, what would be the correct plug and point gaps.

 

Many thanks for help.

 

Andy

[Ade-TR4]

Hi

 

Tyre pressure are difficult - Even the standard size tyres had different pressure, depending which brand you used.

 

Normally, around 22-25 on the front and 25-28 on the rear is a good staring point. Take it for a spin and see how it feels.

 

Plug gap is 25 thou (increase if on sports coil to about 32 thou). Points 15 thou (I think). Someone will correct if I'm typing rubbish!

 

Cheers

Adey

[Trevor S]

I'm in agreement with Adey, although I run my rear tyres (165 x15 radials) on my TR4 slightly higher at 32 psi.

 

(Adey, thought your car looked really good at the weekend, thanks for showing me the original Clayton Dewandre servo. I hadn't seen one before )

Cheers

Trevor.

[stuart]

On my solid axle 4a I run 24 front 26 rear on 165 x 15 Michelin XAS. I found any higher makes it a bit "squealy" as I have a very hard suspension setup.

But it is a matter of personal preference as well.

Stuart.

[Ade-TR4]

Cheers Trevor!

 

The handbook does list 32psi for a some tyres. I've found it a bit "boingy" on my rear suspension setup.

 

What tyres are you using? (I'm on the continental ct82 165x80)

 

Stuart - how do you find the XAS's?

 

Cheers

Adey

[stuart]

Cheers Trevor!

 

The handbook does list 32psi for a some tyres. I've found it a bit "boingy" on my rear suspension setup.

 

What tyres are you using? (I'm on the continental ct82 165x80)

 

Stuart - how do you find the XAS's?

 

Cheers

Adey

Adey they are very good in the dry and can be entertaining in the wet if pushed hard, they tend to outlast their use by date as very hard wearing but if you have to replace them they are only available about once a year and extremely expensive.

Stuart.

[BrianC]

I had XAS's on my first TR3A in the early '70s and they were superb in wet and dry. The compound will have changed dramatically so the current version may be less predictable. Alas, there is no way I can justify buying a set at today's prices, but if I could, I would. One thing, bearing in mind the sporadic availability, is to either buy a couple of spares or at least start searching well before any need replacing (more likely to be due to damage than wear, unless you have a tracking problem) because it is definitely not a good idea to mix XAS's with anything else.

[Trevor S]

I'm using Firestone 165 15 but don't have further details to hand. I increased the rear tyre pressures after 2 or 3 informative articles in succesive issues of TRAction a few years ago by an apparently knowlegeable tyre expert. I only have standard rear springs (without spacers it being a 62 car). Can't say I've noticed any problems with handling in wt or dry, although they did squeal a bit going up Prescott Hill on the ST Forum day, but I would have been going too slow if they hadn't !

In view of all that I've read on tyre age recently I guess I should be replacing them soon as they must be about 10 years old by now.

Trevor

[Ade-TR4]

Anyone tried the Michelin XZX tyre (165/80 R15)?

 

I too am looking at a full new set soon. The XZX seems to look the part.

 

cheers

Adey

[bob-menhennett]

Adey

 

I went for Michelin XZX 165/15 because they "look the part " and Michelin tyres I've had in the past have lasted well.

 

Too early , 2000 odd miles ,to speak from real experience but pleased so far..On Thames Valley's Norway trip in June all four wheels were airborne

when we hit a gouge across the road formed by recent ice and snow, coming down a mountain road.The car suspension hit the bump stop

and it was a bit " boingy" ( to quote you ") for a few moments after that.Wasn't going to check the precise tyre pressures whilst the car was still moving !!

 

Bob

[BrianC]

I went for Michelin XZX 165/15 because they "look the part " and Michelin tyres I've had in the past have lasted well.

...On Thames Valley's Norway trip in June all four wheels were airborne...

That way they will last even longer

One of the frustrating things about Michelins (my favourite tyres), is that although they cost more but last longer, on a TR (or any classic/hobby car) you never get to wear them out before they need replacing due to aging.

They also tend to be a little hard and perhaps better suited to summer driving for the boy-racers (or even geriatric racers), although I've never had any problems using them all year round in the past. I've never tried XZXs but perhaps I'll investigate them as the Klebers on Lynda's TR4A are theoretically past their sell-by date (although with loads of tread left ).

[ChrisR-4A]

Adey

 

I went for Michelin XZX 165/15 because they "look the part " and Michelin tyres I've had in the past have lasted well.

 

Too early , 2000 odd miles ,to speak from real experience but pleased so far..On Thames Valley's Norway trip in June all four wheels were airborne

when we hit a gouge across the road formed by recent ice and snow, coming down a mountain road.The car suspension hit the bump stop

and it was a bit " boingy" ( to quote you ") for a few moments after that.Wasn't going to check the precise tyre pressures whilst the car was still moving !!

 

Bob

 

I agree Bob, correct size looks best, I have just fitted two more 165/15 Firestone F560 to the rear of my 4A having put two on the front last year. These are on standard 60 spoke wires which on the tyre shop ballancer are showing as 4" wide rims, and there lies the problem as the tyres they replaced were 185/70/15 vredesteins which were really too wide for the wires. Over bumps and ridges the Firestones are much better and steering at all speeds up to 80 (don't usually get to go much quicker) is lighter and more positive. So maybe Triumph had it right with the original spec.

 

As a further plus point the recent two Firestones came from "MyTyres" arrived after 3 days for £87 the pair including delivery and fitted and ballanced by my local tyre shop for £10 per wheel.

 

Chris

Edited July 23, 2008 by potts4a

[john.r.davies]

No one's mentioned a tread depth guage.

 

The 'feel' of the tyres with various pressures is subjective, while the wear of the tread, though slow and in a small range, less than 10mm, is wholly objective. Keep a record of the tread depth, across the the tread and see if it is even. Too high and too low pressures are revealed by central or edge wear respectively, and you will spot tracking and camber abnormalities sooner too.

 

John

[Alec Pringle]

Hi Adey,

 

historical information, and compounds may well have changed to some extent. In 1977-78 I did quite a bit of TR and MG tyre testing at Goodwood, with reference to production sports racing. The difference in lap times between XAS and XZX was quite substantial, something around 6 secs on the TR6, around 4 secs for the MGB. The 6 was more capable of exploiting the XAS. In TR6 lap times, 110 against 116 secs. However, wear rate of the XZXs was probably 50% improvement on the XAS'.

 

There are some reasonable Asian tyres available if you search hard - if you're interested I'll go down the garage and look what's on the Super Snipe, they work well under serious load. Past experience suggests that anything that's capable of keeping the big Humber on the road in a 4-wheel drift works well on a TR.

 

Cheers,

 

Alec

[BrianC]

There are some reasonable Asian tyres available if you search hard

In the course of searching for a potential balancer of wire wheels, I visited the local MG specialists, Brown & Gammons in Baldock. They sell Toyo (Japanese) and Nexen (Korean) and have good feedback from customers. I would think that what works on MGB/Cs would work reasonably well on TRs for everday use. Toyo are more expensive and seem to have the better reviews of the two on the internet, but the Nexens get good reports for value for money.

 

Choice of tyres in 165/80/15 size is limited (at least on the high street - greater choice on the internet) and I suspect suitable tyre pressures will vary considerably between brands and from the original Triumph recommendations based on the tyre technology of the period. I usually start with the original recommendation and adjust to suit, but keeping roughly the same front/rear balance. Beware the very low recommended pressures for Michelins - I assume these were specific to the original '60s Michelin X tyres which were designed to run at lower pressures than the rival Dunlops, Goodyears and Firestones. I tried running the TR4A Klebers (manufactured by Michelin) at these pressures and rapidly increased them, although the Michelin technical support suggested using the original (low) pressures.

[stuart]

I did try running the low pressures quoted from Police TR4s and found that when pushed hard the fronts were trying to roll off the rims and more wear was present on the outside edges.

Stuart.

[Ade-TR4]

Cheers Alec,

 

No rush as I'm not changing them until the winter-time, but any info greatly appreciated. 4-wheel drifting a Humber sounds interesting!

 

I had 185/60 on wider minilites for a while and the TR4 was very strange to drive. Now on ARE's and original profile/ width, the car feels great and rides well too.

 

Thanks all,

Adey

[Nigel Lay]

I have now run the Nexen SB802 (165x15) for a few thousand 'hard' miles and I am chuffed to bits with them, there seems to be a tie up between Nexen & Michelin somewhere along the line. I run them at 26 & 28psi.

Nigel (with TS952)