Tyre fitments

[alannoble]

Hi all,

Can anyone advise me whether I can/ would it be wise to, fit 185/60 13 tyres to the rear of my Vitesse .I realise there will be some alteration to the gearing, but I am already running a 3.63 diff. Any answers, negative or positive would be appreciated!

Regards

Alan

 

[Pete Lewis]

here you can play with tyres/diff ratio and compare 

www.mintylamb.co.uk/gearspeed/

Pete

[cliff.b]

2 minutes ago, Pete Lewis said:

here you can play with tyres/diff ratio and compare 

www.mintylamb.co.uk/gearspeed/

Pete

How wide are your wheels?

And what size tyres will be on the front?

[Clive]

41 minutes ago, alannoble said:

Hi all,

Can anyone advise me whether I can/ would it be wise to, fit 185/60 13 tyres to the rear of my Vitesse .I realise there will be some alteration to the gearing, but I am already running a 3.63 diff. Any answers, negative or positive would be appreciated!

Regards

Alan

 

Not a vitesse, but my Rotoflex spitfire. 

On a non roto car, I would definitaly hesitate. The camber changes mean a 60 profile is possibly a bit "thin". On a rotoflex car rather less of an issue. 

Apart from that, wheel with (you need 5.5J width) and correct offset will be critical to clear the bodywork. 

The car will look a little odd unless it sits a little lower than standard, the gap will be too big. 

I am also intrigued about what you intend for the front.

[alannoble]

5 minutes ago, clive said:

Not a vitesse, but my Rotoflex spitfire. 

On a non roto car, I would definitaly hesitate. The camber changes mean a 60 profile is possibly a bit "thin". On a rotoflex car rather less of an issue. 

Apart from that, wheel with (you need 5.5J width) and correct offset will be critical to clear the bodywork. 

The car will look a little odd unless it sits a little lower than standard, the gap will be too big. 

I am also intrigued about what you intend for the front.

I should have said 2 Litre mk2 

[Clive]

1 minute ago, alannoble said:

I should have said 2 Litre mk2 

So camber change not a problem. 

But of course the elephant in te room is why the 185/60 as opposed to the usual 175/70?

[alannoble]

With the back end always a twitchy I was wondering if a wider profile might be appropriate 

[cliff.b]

16 minutes ago, alannoble said:

With the back end always a twitchy I was wondering if a wider profile might be appropriate 

Have you experimented with tyre pressures? I've found it can make quite a difference

[chrishawley]

Comparing 185/60 r13 (say) 155/80/ r13 that's about a 5% reduction in rolling radius; so what was for example 4000rpm will now be 4200. The body of the car would be lowered by about half an inch in relation  to the ground.

But if the underlying concern is something unstable about the rear suspension there may be matters to consider other than tyres. For example if 'twitch' at the rear takes the form of 'bunnyhopping' or 'sidestepping' then examination of the toe-in would be warranted. Which would be either a DIY job or a laser alignment jod depending on one's resources, skills, wallet and opinion.

[NonMember]

1 hour ago, alannoble said:

With the back end always a twitchy I was wondering if a wider profile might be appropriate 

I doubt it will help. There are many reasons why the back end might be "twitchy", but narrow tyres is not one of them.

[Clive]

12 hours ago, alannoble said:

With the back end always a twitchy I was wondering if a wider profile might be appropriate 

a few things to check, some mentioned already, 

1. Tyre pressure, too hard will make skittish. Or if the tyres are old.

2. Shock absorbers. If adjustable, set them soft as you can, test and then adjust up until you are happy. Mid way is often FAR to hard, on Gaz, they can be solid at just 5 clicks.

3. Rear wheel aligment. If incorrect the cars are terrible. Search the forum for a "how to" 

[Pete Lewis]

here you go two sticks and a tape measure 

and dont forget most triumphs need 150lbs on each seat to set the suspensionin its static ride height or you waste time and money 

some specs on later cars do give unladen  but many are not 

if you get bunny hops and a twitch from the rea then the Toe is wrong    very common problem but you dont need lasers  to set it up 

Pete

[rlubikey]

Alan, what was the original fitment on a Vitesse and what do you have on there at the moment? I had 185/60R13 for a while on my old Spit and they looked too small to my eyes. They just didn't fill the arches as Michelotti intended. I have 185/65R13 on my new Spit and they are much better, but now unobtainable - unless you know better! So I've just bought 175/70R13 which will be fitted shortly. 175/70 are virtually the same rolling radius as 155/80R13 which would have been original fitment on later Spitfires.

Cheers, Richard

[NonMember]

2 hours ago, rlubikey said:

what was the original fitment on a Vitesse

5.60 cross-ply 😛

Or 155R13 (I think they were 155/85-ish but 155/80 is close) on the 2L models

Edited May 18, 2022 by NonMember
Correct an error

[Gary Flinn]

I had 185/60 x 13 Tyres fitted to 5.5J Alloys on my first Vitesse Convertible way back in the late 1980's

The car stuck to the road like glue in the dry but was terrible in the wet, especially the back end

The Tyres I had fitted were the old Goodyear Eagle NCT's, so I'm not sure if it was these that caused it to be a handful in the wet or the profile of the tyre?

I fitted 175/70 x 13" Uniroyal Rain Expert tyres on 5.5J Rims to my last Vitesse, sold in 2015 and this was a good combination in both the Wet and dry, a better ride quality too 

Just remember you still get some camber change even with the Roto-flex rear suspension (3 or 4 degree's at a guess), although no where near the amount of the earlier Swing Axle set up.

Regards

Gary   

[Nick Jones]

As already suggested, check the rear toe settings. Should be 1 -3mm toe in at normal running height. 

Also well worth checking that all bushes (radius arm, inner wishbone and spring eye) are good.

Are the lever arm dampers still in place? They are not the greatest even when in top shape……

Tyres wise I’ve always run 175/70s on mine, first on 5.5” wheels, now on 6”. It’s very stable and progressive even when caning it on the track. Can’t quite keep up with Clive but he does have a few more horses and a bit less weight…..

Nick

[Clive]

8 hours ago, Nick Jones said:

Tyres wise I’ve always run 175/70s on mine, first on 5.5” wheels, now on 6”. It’s very stable and progressive even when caning it on the track. Can’t quite keep up with Clive but he does have a few more horses and a bit less weight…..

Nick

They are needed to compensate for my skill level. But I reckon my spitfire is no lightweight. gearbox and diff are quite hefty. Not to mention the driver.