| Author | Message | ||
     James Feller Frequent User Username: james_feller Post Number: 64 Registered: 5-2008 |
Hi All, Well I thought it was time to share the Big Blue with you.... The one issue I have is with the bloody tyres... they are not Avons, they are Yoko's. The previous owner had to put them on about a year ago as there was no Avon's in Aust a year ago. They are not the correct size of 255/65's either, they are 255/60's. They have the correct speed rating though. My problem is the inaccuracy of the speedo currently. I have read if you change the tyre size you need to get a new speedometer drive gear. Would this be why when the speedo says the car is doing 60klms it really is about 75klms? Anyway, I have ordered the right Turbospeed CR27's for it, but its an 8 week wait!!!!! but the extra omphh of this car compared to my Spirit is simply intoxicating!!! I love it! the Spirit is feeling a little neglected at present... J     | ||
| David Gore Moderator Username: david_gore Post Number: 899 Registered: 4-2003 |
"Tis indeed a lovely car Sir" [paraphrasing the classic Bisley shirt ad from times long ago]. | ||
| Richard Treacy Grand Master Username: richard_treacy Post Number: 1852 Registered: 4-2003 |
This chart may help. If you can't read it, I'll search the Technical Library for the same chart. You will see that when the speedo reads 100, you are really going a only little slower at 96.25. That is well within range. You can buy a new plastic driven gear with one less tooth from a transmission shop and fit it easily if you want the speedo to be dead accurate, but 5% error in the overreading-speedo direction is the industry standard for homolgation anyhow. Underreading is illegal by ISO, European, Australian and ACEA etc. standards. Assuming that you still have the old 15" rims and are looking for 255.65R15 106V then that archaic Avon is the only brand in that size, and the design is an ancient one adapted in 1984, and only in size, from one from around 1970. You can do much better than that old rubbish. I would stay with the Yokohamas or something else if you dont like the Yokos, and forget Avons forever. On your car, a standard 235.70x15 101V SY or SZ tyre is fine for Australia too with the silly speed limits. The extra 20mm nominal width is negligible once on those rims. In fact, 235s work a little better as those 7 ½ rims are just too narrow for the 255s. I have 17 rims, and gave my ancient 15 rims and near-new Avons away free to a fellow in Germany, ditching them for obvious reasons. Also, I steered well clear of Avons, even in their newer-design 17 255.55ZR17 102W and went for Michelins of the exact size rating (255.55ZR17 102W , that's a 270km/h tyre). When Michelins went out of production in 2007, I switched to excellent Nokian 255.55VR17 108W tyres, a 2008 design. I have just put a spare set on the ship in case I damage one as they are not a line stock in Australia at the moment. They came from: http://www.reifendirekt.de/ RT.  | ||
| Richard Treacy Grand Master Username: richard_treacy Post Number: 1854 Registered: 4-2003 |
Note that, in the above table, there is a decimal point missing in the Nominal Diameter column. 255.60x15 has a nominal diameter of 687.0mm and as-produced 686mm. and ps: I am sure that you could still cancel the order for Avons. They are very inferior tyres and far too expensive as a final insult. | ||
| Richard Treacy Grand Master Username: richard_treacy Post Number: 1855 Registered: 4-2003 |
Here were the Nokians ready to ship.  | ||
| Richard Treacy Grand Master Username: richard_treacy Post Number: 1856 Registered: 4-2003 |
The tyre size and axle ratio chart is in the Texchnical Library under Miscellaneous Technical at: http://rrtechnical.info/miscellaneous/tyresizesaxleratio.pdf | ||
| James Feller Frequent User Username: james_feller Post Number: 65 Registered: 5-2008 |
Thanks guys, Richard my issue is the noise the Yoko's make at low speed.... its like a 4 X 4 sort of whirring noise... just awful and its the tyres as I had this checked. RT, I know you are not a fan of the orginal Ronal Alloys but I like them so yes they are the orginal 15' alloys. I might take it to my tyre guy on Saturday and see what he recommends I have only discussed this over the phone with him. Yes Richard your right its never too late to cancel the Avons but they are quiet, I take your point they are not cutting edge tech stuff these days. Cheers J | ||
| Dr. Omar M. Shams Experienced User Username: omar Post Number: 30 Registered: 4-2009 |
James, If the tyres are not directional, try swapping them so they turn in reverse to the way they are turning now. Sometimes this reduces road noise that can get transitted through minor feathering of tyres that have been previously rotated........ nothing to lose but a little efort. I have to live with my tyre noise becasue I have 18" rims and the tyres have to be a 45 profile to fit. good luck Omar | ||
| James Feller Frequent User Username: james_feller Post Number: 67 Registered: 5-2008 |
Ta Omar, I saw the guys at my tyre centre and they laughed at the Yoko's on it and said, 'great tyre should stick well and good on corners but bet its noisy...' yes was my answer trying to cover their smugness... No they are not directional Omar, rotating would do no good as the tread pattern is aggressive right to each sidewall. Due to the odd size tyres made for these cars, 255/65, I really am very limited for choice with the original alloys of 15'( I could change the alloys but I like them, I am keen to keep the car VERY original as its one of only a few RL's originally delivered by York Motors in Aust and with 105klms on it for its age, its rare) So looks like I will wait for the Avons to come in... I know Richard, but I don't have much choice other than a Pirelli which again I have to wait for... ta for the advice though it is appreciated. Cheers J | ||
| Paul Yorke Grand Master Username: paul_yorke Post Number: 377 Registered: 6-2006 |
James, Richards note about fitting the 235's should definitely be a serious consideration on your 15" wheels. Isn't the speed rating the same Richard? The wider Avons will run the outer edge off them in no time at all. London dealers were forced to tell clients that 6000 miles was acceptable and there is nothing wrong with their cars! Ouch. They will look original too  Raise the tyre pressures as well. Also ensure that the front upper lever bushes and compliant mounts are in good condition. Both tyre killers. RE: the speedo, it it the same % difference over the whole range or is it 19 MPH over the whole way? | ||
| James Feller Frequent User Username: james_feller Post Number: 68 Registered: 5-2008 |
Hi Paul, Thanks for your note. Funny you mention the % difference, I dont think it is a consistant difference the whole way through the range . Meaning when the speedo says 30klms its going about 40klms, at higher speeds at say 80klms its true speed is closer to 100klms.... what do you think this is Paul? is it the tyres or the speedo gear drive? Re control arm bushs and mounts these have all been checked and are in good order. You mean I can put on a 235??? hmm interesteing will consider it. Cheers J | ||
| Paul Yorke Grand Master Username: paul_yorke Post Number: 378 Registered: 6-2006 |
Hi James. Ok that sounds like it is a % difference - as opposed to just being 15 kmh down across the whole speed range. (Means it's a mis-match somewhere and not just the needle on in the wrong place.) Yes 235 70 15 VR tyres are what are most often fitted on Turbo and Nat-Asp cats here these days. MUCH cheaper and last longer. | ||
| Stefan Morley Experienced User Username: myupctoys Post Number: 11 Registered: 7-2009 |
Hi Peoples, Keeping an eye on this topic as its a perennial issue for Turbo R's. I dealt with it by importing AVONs. Cheaper than sourcing locally but still pretty stiff. The question. How do isurance companies view tyres not following manufacturers specs explicityly. Imagine if its load and speed rated probabaly not an issue but there arent too many tyres that fit the catagory. Certainly if road noise is also taken into account. I doubt too many of us take our cars to their limit so wonder if a lower speed rated tyre with correct load rating might be an out for insurance purposes. Stefan | ||
| Ross Rackham Experienced User Username: rosco Post Number: 16 Registered: 8-2009 |
Stefan, I think you have a very valid point. Do you really need a high speed rated tyre. I cruised from Bris to Canberra in my Shadow I at about 120-140kph. Why would I need a tyre rated over 160kph. And how often would I really use them to their limits. When it comes to bikes, fine, I regularly do between 160-270kph (much to the annoyance of the local police) so I have appropriately rated tyres. But for a car designed for cruising, why pay for what you're never going use. I can't comment on what the owners of the more modern RR/Bent owners do but excessive overrating of tyres seems a bit of a waste. As long as the load rating is correct for the speeds you are using, why pay for extra. Cheers Ross | ||
| Paul Yorke Grand Master Username: paul_yorke Post Number: 379 Registered: 6-2006 |
I've had a discussion with an insurance engineer and his thinking was along the lines of - if you have a crash where you go into the back of someone on a motorway ar off the road on a fast bend, then tyres will be brought up and may negate a claim. Get a rear end shunt or a car park knock, or around town bump - and it wont matter. The worrying 'BUT' was . . . if they hadn't managed to meet there estimate reduction target for the month - anything goes! | ||
| Richard Treacy Grand Master Username: richard_treacy Post Number: 1867 Registered: 4-2003 |
Speedo: Someone has put a standard SZ drive gear in your gearbox for sure. The discrepancy matches the final drive ratio difference between the Turbos and wimps. Exchange overhauled transmission Ill bet. Always a dodgy way to go rather than having your own rebuilt. Tyres. Best bet: go for a 225.75x15. The rating should be 102V or higher. They are plentiful. That applies to SYs too by the way, although all SYs and SZs are ridiculously overshod width-wise for the skinny rims provided. A 255 as fitted to a Turbo R needs a rim of 8 ½, and the factory 7 ½ is too narrow in reality. The early 275s were literally falling off the rims. If you want a squishy and noisy 6,000 mile tyre, go for an Avon. If you want a brilliant 60,000 mile tyre, go Japanese or Finnish. In general, without an Engineer's certificate in Australia, insurance follows legality. The cops will hammer you before the insurance company squeals. Gone are the days when alloy wheels trebled your premium. Without a certificate, you may follow the rigid +/-1 rule and rest easy. A wheel, rim or tyre diameter or width may individually deviate from the manufacturer's original OR optional measure by 1" plus or minus. So, you may go as low as 14 or as high as 22 in rim diameter, and a rolling radius of 28 to 30. Rim width must be in the range of 5 to 8 ½ . Load rating for SY and SZ cars must exceed 101 and there is no compromise on that whatsoever. The speed rating and load rating are rigid, but an Engineer's certificate may allow a lower speed rating given the silly speed limits in our country. Even an S rating is fine, but most even cheap tyres these days are at least V speed-rated. So, for a 255.65x15 106V, that Exceeds Crewe's specification of 101V. Avons are 106V. Late Continental R and Turbo Rs run 255.55x17 102W, so even Crewe dropped the load rating. My Finnish Nokians are 108 whereas my Michelins were 102 Continental R W-rated tyres. Tyre width. You may use tyres in the range 195.x15 to 295.60x15. Early Turbos had those horrendous Pirelli 275s before Avon stumped up with a rough and ready bag, so plus 1 is file at 295mm. | ||
| Richard Treacy Grand Master Username: richard_treacy Post Number: 1869 Registered: 4-2003 |
ps. you guessed it. An Avon is about 20 times more expenive per kilometer driven than a Toyo or a Nokian as examples, and the latter two perform far better under all conditions. | ||
| Richard Treacy Grand Master Username: richard_treacy Post Number: 1872 Registered: 4-2003 |
pps: you will never find a tyre rated for less than 160 km/h. Even for a Jeep or a White Van. This old photo from 2005, when I was slowing down sharply after the needle hit the stop and bent, shows that sometimes a quick getaway is needed. And yes, the speedo is 100% accurate, as the registration check on the test loop radar showed exactly 100km/h with 100 on the inner speedo km/h readout. Note the dropped RPM due to the torque converter. It was pegged on 4500 for quite a while before I reached for the camera.  | ||
| Richard Treacy Grand Master Username: richard_treacy Post Number: 1874 Registered: 4-2003 |
ppps: Paul Yorke quotes:
Narrow rims, large tyres. That's why tyre manufacturers hate Crewe. The rims are seriously too narrow for the tyres that Crewe fits. That is precicely the reason why Michelin has refused to OEM tyres for Crewe since the fitment of radials. The others followed in droves, leaving poor old Avon as the bridesmaid. When I went down from 235.70 Avons on the T-Series to P215.75 Michelins, then Bridgestones, the behaviours was a leap into the next, now this, millennium. | ||
| Bill Payne Experienced User Username: wimpy Post Number: 21 Registered: 1-2007 |
Ross Rackham quote: Do you really need a high speed rated tyre. While you may indeed save a little, going with a higher speed rated tyre gives you additional handling/performance advantages in dry and wet conditions that are well worth the extra expenditure. If you habitually are using the slow lane, never drive in damp weather and always drive within the mandates of the state, then by all means buy the cheapest round doughnut you can find. | ||
| James Feller Frequent User Username: james_feller Post Number: 69 Registered: 5-2008 |
Hi All, Just an update, well what can I say.... the right tyres make all the difference. Richard I took your advice and cancelled the AVON's. After a recommendation from tyre experts in Sydney I went with Toyo Maxiis I think... something like that, they are 275X65X15's. They were not that dear either about $400 each as opposed to $1200 each for the Avons. The tyres now look right in the wheel arches and the car now sits higher as it should. Wonder of wonders my speedo is now spot on, this clearly shows the dramatic effect a set of incorrect tryes can have. Best of all the new tyres speed rating is what it should be for the car and its nice and QUIET!!! Thanks all for your advice, it was appreciated. J | ||
| Richard Treacy Grand Master Username: richard_treacy Post Number: 1899 Registered: 4-2003 |
Well done. Toyo is a favourite brand of mine ! I have had several sets on my BMWs and they are great. R. |
