# Talbot Express wheels



## martyb (Aug 8, 2009)

Hi all,hope we are all well?
Whilst away last week in the the new Forest I had a puncture. So What I hear you ask. On ringing around and looking for a replacement I was looking at a wall chat showing tyre pressures,sizes etc.  My eye was drawn to the Fiat Ducato which is a 15" Wheel, My Talbot is running on 14". Would it not be better for the gearing on mine to be on 15" wheels, so as it is not screaming so much at the 60/70 mph mark? Sorry for the waffle...


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## Tco (Aug 8, 2009)

Indeed and some are on 16" wheels.  You'd have to be aware that it would alter the gearing and as such the speedo may be out of tolerance. This may have implications at MOT time.

I have just replaced the tyres on my Boxer (same thing) but I went up a size from 215/70-15 to 225/70-15  I have found that my speedo is now right (checked agains GPS) after having previously been about 10% "fast"  That is on a tyre that is only 10mm wider for the same aspect ratio.   So going up an inch on rim size would have a significant effect.  

Check also the tyre clearances, particularly on full lock to make sure that the tyres do not fould anything.

Tco.


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## lebesset (Aug 8, 2009)

speedometers are always set to show a higher speed than the reality , and upgrading by one size is very unlikely to cause an under-read [ most over-read by 5-7 % ]

on the other hand the odometers are much more accurate , and you may well travel further than is registered


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## mildred (Aug 8, 2009)

*Talbot Express rim sizes - speedo readings - gearing - CV joints*

Afternoon All!

There's just been quite a back and forth about Talbot wheel sizes on the Preloved forum - starts on pg 168 and goes on ...

That started because a couple of us were unable to get good road speeds from our 2.5Ds  although engines were in good shape and the speedo was registering a reasonable speed. Conclusion is that at some time the gearboxes and ancillary parts have been swapped for bits from the 3.5 Maxi which came with 16" rims and beefed up suspension, braking and CV joints.

If you go this route things to bear in mind are clearance as has already been mentioned and that you'll have a lot more back-leverage on steering components.  There will also be greater unsprung weight.  It's possible that simply putting bigger rims on might  get you into more problems with wear and handling. 

I don't have a current MOT manual to hand but I'm fairly sure that the accuracy of speedo is still not checked at MOT
Edit: It's not checked at MOT, however a functioning speedo is a Construction and Use requirement - which is what roadside checks go by. 

The law on Speedos as quoted in Hansard no less:

The Road Vehicles (Construction and Use) Regulations 1986, as amended, allows the use of speedometers that meet the requirements of EC Community Directive 75/443(97/39) or ECE Regulation 39. Both the EC Directive and the ECE Regulation lay down accuracy requirements to be applied at the time of vehicle approval for speedometers. These requirements are that the indicated speed must not be more than 10 per cent of the true speed plus 4 km/h. In production, however, a slightly different tolerance of 5 per cent plus 10 km/h is applied. The requirements are also that the indicated speed must never be less than the true speed. 


Regards,

M


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## lebesset (Aug 8, 2009)

tried to edit my previous post without success 

http://www.kouki.co.uk/utilities/visual-tyre-size-calculator

you can check the effect of any change you would like to make with this

don't understand Tco's post ; the difference between the 2 sizes he quotes are only 2.1% !


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## Tco (Aug 8, 2009)

lebesset said:


> tried to edit my previous post without success
> 
> http://www.kouki.co.uk/utilities/visual-tyre-size-calculator
> 
> ...



I know! I simplified the maths to make a point. I noticed after I fitted the GPS that the speedo and the GPS did not agree on the old tyres. (perhaps the 10% was a bit of an exaggeration) but since the new tyres have been fitted, the speedo and the GPS more or less agree. However there is a difference between the circumference of a tyre and the rolling circumference as the tyre deflects under load. Also the old tyres had worn down somewhat and having a lower load index the actual rolling circumference difference would be greater than the 2.1%. Particularly as the new tyre has a deeper tread and a higher load index which would mean that the deflection would be less for the same load.  

Sorry didn't want to complicate matters.  

Tco


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## mildred (Aug 8, 2009)

*tyre size calculator*



lebesset said:


> tried to edit my previous post without success
> 
> http://www.kouki.co.uk/utilities/visual-tyre-size-calculator
> 
> you can check the effect of any change you would like to make with this!



[Edit: stuff deleted - I confused Load Index with profile percentage]  I think the only way to really sort it out is get out a ball of string, measure the actual tyre circumference and do a lot of sums  - then check with a surveying grade GPS  and good mapwork.  

Alternatively - if you have a tailback behind you when you're doing an indicated 60, you can pull away in second or third, you think you're getting almost 40 mpg, you don't/do trigger spe^H^H^H safety cameras when you *should/shouldn't* have- then you might well have a tyre mismatch ...


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## lebesset (Aug 8, 2009)

102/100 is the carrying capacity 
your tyres will be 80 aspect ratio if not marked as lower


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## martyb (Aug 14, 2009)

Ok I think by the sounds of it I will keep them as they are. I Will ring the talbot specialist and see what he has to say...playing it safe.. Thanks all


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## martyb (Aug 22, 2009)

I was also wondering if there are any alloy wheels that would fit the van? I am just thinking of trying to spruse the old thing up as it is slightly square...lol  Any ideas please  ta.


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