Talking of tyres.....

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cavmad
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Talking of tyres.....

Post by cavmad » Mon Aug 01, 2005 5:03 pm

....I also have 165-70-14`s on my diesel on standard rims. Being an ex-tyre fitter I should probably know this but how much difference would it make if I fitted 175-70-14`s to the standard rims? I only ask because the two fronts are due for replacement soon and I have stacks of nearly new 175`s which I can fit myself.
I know the `175` part will mean 10mm wider and the height will be slightly effected (the `70` bit meaning 70% of the 175) so I`d have thought it would be o.k.
However I`d appreciate if anyone who`s done a slight change in tyre size at all letting me know their opinion and whether they`ve had any after effects of doing so?

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Post by jeremy » Mon Aug 01, 2005 5:17 pm

The normal size used is 175.65 x 14. As you know a 70 series will have a slightly greater diameter/circumfrence and will probably make the speedo more accurate (on the basis that most overread!). Its interesting thatthe standard sizes used on the larger engines BX all seem to produce the same diameter - eg 195/60 x 14 for 16 valve (which is about as big as will fit in the arches!)

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Post by Vanny » Mon Aug 01, 2005 6:04 pm

got to say that of the the BX speedo's i've had they have all been spot on with the standard tyres setup from the 20's way upto the 80's. First one was checked at santa pod when crossing the finish line, and by my reckonin it was spot on! Last time i checked by following my dad in his picaso at night, you can see the display from behind the car anyways, but i had him stick at dead on 30 and mine matched (he gets it recalibrated pretty often as well!)

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Post by cavmad » Mon Aug 01, 2005 6:52 pm

jeremy wrote:The normal size used is 175.65 x 14. As you know a 70 series will have a slightly greater diameter/circumfrence and will probably make the speedo more accurate (on the basis that most overread!). Its interesting thatthe standard sizes used on the larger engines BX all seem to produce the same diameter - eg 195/60 x 14 for 16 valve (which is about as big as will fit in the arches!)

jeremy
Cheers, appreciate it. If the standard size is 175-65-14 then I don`t feel that the 70 series will make that much difference, except perhaps the extra weight of the tyres adding to the biceps on my arms due to my disticnt lack of power steering!
The 60 series tyres fitted to `sportier` versions of the BX will amost certainly be down to the extra grip and the higher speed rating of these tyres. this also means that you can`t fit tubes to them either so if your rims go porous or they start flaking around the rim you`re going to have a lot of `fun` trying to get them to seal permanently. Just ask anyone who owned an MG Metro with metric rims, I`m sure they`ll tell you!
Having said that fitting tubes isn`t that clever anyway. It`s illegal and dangerous to fit them to punctured tyres unless you repair the hole in tha tyre at the same time-so tubing it would be pointless anyway. Also if you get a nail or something similar stuck in the tyre a tubed tyre will deflate immediately, probably with a big bang and loss of control. A tubeless will go down slowly and you should notice before it goes completely flat.

My old boss used to reckon if you put a postage stamp inside a tubed tyre (i.e between the tyre and the tube) eventually the stamp will puncture the tyre. I`d now only fit tubes to cars where the wheels won`t seal at all due to rims flaking etc, but would rather replace the wheels than run the risk. It used to amaze me what I used to find in tyres-an ornamental letter opening dagger, teaspoons, dessert spoons-all kinds of things. They usually puncture the tyre when it is wet because they become far more susceptible to flats in the wet, and it`s usually the rears which go because the front tyres pick the objects up and they are then `thrown` at considerable speed towards and into the rear tyres.
Interestingly enough (well, it`s interesting to me!) they now recommend fitting remoulds/part worn/budget tyres to the front now as opposed to the rear. Completely different to what they used to say but apparantly the vehicle is more likely to lose control with a rear puncture than it is with a front one.

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Post by Mr B » Mon Aug 01, 2005 7:03 pm

http://www.chris-longhurst.com/carbible ... bible.html

Have a look here and you can put in the size of both tyres and work out the rolling diameter to compare
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Post by cavmad » Mon Aug 01, 2005 7:23 pm

Mr B wrote:http://www.chris-longhurst.com/carbible ... bible.html

Have a look here and you can put in the size of both tyres and work out the rolling diameter to compare
Fantastic site, thankyou. Interestingly the boy racers will be a little gutted if they use the info on there. Putting their 19" rims onto their Nova/Corsa/Fiesta might look lovely and bling but the speedo will be out a fair way and would suggest the car is going slower than it is. A few problems here: firstly the chance of a speeding ticket increases as they`ll technically be speeding, perhaps just enough to trigger a speed camera. Secondly their insurance company need to know or they`ll come very unstuck as lots of people have in the event of a claim. Thirdly when they sell their beloved Bazmobile the potential purchaser will think the car is slow and finally (although most are oblivious to this) they look complete tw*ts anyway. Why some choose to advertise this even more with drainpipe exhausts is beyond me but there you go!

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Post by Mr B » Mon Aug 01, 2005 9:23 pm

My BX ran 165/70/14's and when bought the 16V alloys ended up with 2 decent 195/60/14's. The difference between the 2 sizes at 70mph is 0.36 mph. Which is nice.

8) Graphite 16V alloys wearing 195/60/14’s - It’s a winner! 8)
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Post by cavmad » Tue Aug 02, 2005 6:24 pm

After all that I`ve found 3 good 165-70-14 tyres in my garage when rooting around for the 175 ones I had!
I also found a few more part worn and three new tyres I forgot I had amongst the mound of Cavalier parts and the Escort van which I`ve chucked on eBay.

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Post by Stewart (oily!) » Tue Aug 02, 2005 8:25 pm

The only BX I have owned that felt right on 165s in the wet was a 1.9N/a diesel formerly owned by my siblings, it was on rather new uniroyals, my own 165 shod ones sufrered from heavy wear on the fronts and there was no overabundance of grip either, they tend to look a little better on 175s but for me 5and a half Js and 185s on a GTI meant no looking back, I currently run 195s on 6j graphites and have stopped wheelspinning off roundabouts now :D
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Post by cavmad » Tue Aug 02, 2005 8:39 pm

I`m waiting for Mrs Cavmad`s mate`s son to get back from a stint abroad. He has a 205GTi with 1.9 alloys and nice seats that he wants me to collect and take to a grage to get the engine taken out. The resr of the car then becomes my property so anyone want to guess where the wheels and front seats are going to end up?!!!
I have to say my 1.7 n/a diesel handles very well on its 165 tyres, a bit of squeal on tight corners and roundabouts at speed but years of watching the Sweeney makes me think I`m cool!
As an aside Mr Oily have you ever visited a Citroen specialist near Oswestry that used to be in Ellesmere, Shrops?
Can`t remember their name alas, it was something Techniques. They specialised in older Citroens. Used to call their with my old job-nice friendly bunch but hard to find.

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Post by Stewart (oily!) » Fri Aug 05, 2005 3:42 pm

Yes I have visited them, I live about five miles from there, I think theyre called installation tecniques or something, nice guys but they dont get their spanners on my motors :D handy for parts though, and they stock hydrorincage.
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Post by cavmad » Fri Aug 05, 2005 6:05 pm

That`s the fellas, nice blokes as you say. Somewhere near Weston Rhyn if my memory serves me correct. Did you ever go to their old place near Ellesmere? They had what can only be described as a stunning mansion house, in fact the nicest house I`ve ever seen. It was like a fairy tale mansion and had wonderful old out buildings full of rare old Citroens. You must live in a nice part of the world to live within five miles of where they are now.

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Post by Jaba » Fri Aug 05, 2005 9:51 pm

Speedo accuracy??

All cars used to have very optimistic speedos. Citroen BXs started to reverse that trend. My GTi and TZD both read only 4% optimistically.
My Xsara is spot on! I measure this on a motorway by timing between one or two kilometres at a steady speed and doing the calculation.

Personally I prefer a speedo that says you are going a bit faster than you really are. It gives a small safety margin when the speed radar has a look at you.
The Joy of BX with just one Citroën to my name now. Will I sing Bye Bye to my GTI or will it be Till death us do part.

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Post by cavmad » Fri Aug 05, 2005 10:57 pm

Speed is one thing I don`t have to worry too much about. Citroen`s finest 1.7 n/a diesel has seen to that!

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Post by tom » Sat Aug 06, 2005 9:10 am

The reason for remoulds going on the front is to increase understeer by biassing the grip to the back. Apparently it is safer than oversteer.
The right place for remoulds, (Rally cars excepted) is around gunwhales.