mike.cook Posted April 8, 2009 Share Posted April 8, 2009 HiI'm thinking it might be time to replace my aging crossplys for safety's sake. I have standard wheels as originally fitted to my 13/60 convertible.Can anyone tell me what is the most appropriate tyre size?ThanksMike Link to comment Share on other sites More sharing options...
Clive Posted April 8, 2009 Share Posted April 8, 2009 155 13 (often referred to as 155/80 13 these days) Link to comment Share on other sites More sharing options...
Raider Posted April 8, 2009 Share Posted April 8, 2009 Yes -155/80R13s and they'll make a huge difference from the cross plies :) Link to comment Share on other sites More sharing options...
mike.cook Posted April 8, 2009 Author Share Posted April 8, 2009 Many thanks guysMike Link to comment Share on other sites More sharing options...
junkuser Posted April 8, 2009 Share Posted April 8, 2009 I am a somewhat confused by these tyre sizes Clifty.Have been running 155 13 on the Spit and very happy with them but require replacements.Looking at http://www.mintylamb.co.uk/?page=tyre.htm the comparator shows 155/80 R 13 to have a lower profile than 155 R 15 Imperial, which I presume is what I have.Any ideas? Link to comment Share on other sites More sharing options...
valencia1 Posted April 8, 2009 Share Posted April 8, 2009 the 155 part is the width of the tyre, the 80 part is the tyre height, bead to tread. regards, bryan Link to comment Share on other sites More sharing options...
junkuser Posted April 9, 2009 Share Posted April 9, 2009 Thank you for your response Valencia but my post must must not have been clearly expressed.I was interested to know if tyres labelled 155 13 were the same as some labelled 155/80 13 as suggested by Clifty, or, if the tyres I have are 155 13 Imperial which the Mintylamb site says are are of larger diameter.Tyre sizes can be a little tricky.Way back in the dim and distant past, when bias plys were the norm, I worked in a family tyre retreading business, The most popular tyre size on the market, which was original equipment for Holden, was discontinued and people were forced to use a tyre labelled as a larger cross section size.The interesting thing was that this "larger" tyre fitted correctly into the same retreading mould fitted with the same tread matrix as used for the original size!The new size tyre was naturally more expensive to buy new than the original.Looking at modern radials suggests to me that labelled tyre dimentions may still be a little elastic. Link to comment Share on other sites More sharing options...
valencia1 Posted April 9, 2009 Share Posted April 9, 2009 tyres labeled 155 are taller than tyres labeled 155/80 which has a lower profile. a 155/60 would be an even lower profile. hope this helps.regards, bryan Link to comment Share on other sites More sharing options...
Clive Posted April 9, 2009 Share Posted April 9, 2009 I had assumed that 155/80 was a direct replacement for the old 155's, so I have learnt something. Thought it was just being modern, but they are the tallest available in any case.Just looked at the site. Not convinced the old 155 were "imperial" 100 profile height. They are much bigger than the 155/80, and side by side the old and new 80 profile look to be the same. If that makes sense. Maybe imperial is for crossplies or something else? Link to comment Share on other sites More sharing options...
Deleted User Posted April 9, 2009 Share Posted April 9, 2009 "Normal" profile tyres are 80 profile, so if there is no profile mentioned, it is 80."Low" profile tyres have a profile that is less than 80, eg. 75, 70, 65, 60 etc"High" profile tyres have a profile that is greater than 80, eg. 90, 100 etc.With very few exceptions, tyre sizes are a mix of imperial and metric measurements.The diameter of the wheel is in inches, the width of the rim is in inches, but the width of the tyre is millimeters.The profile is the ratio of the width of the tyre to the height of the rubber around the outside of the rim.There are a small number of cars around that have metric wheels - like the original Metro, and tyres for these cars are very difficult to find, and as a consequence they are very expensive. Link to comment Share on other sites More sharing options...
Keith Posted April 9, 2009 Share Posted April 9, 2009 I'd be wary of using 155x13 on 3.5J rims, I've used 145x13 for many years which are fine.K Link to comment Share on other sites More sharing options...
Goody Posted April 9, 2009 Share Posted April 9, 2009 All I Want Is One's With WhiteWalls! Link to comment Share on other sites More sharing options...
neilnaz Posted April 9, 2009 Share Posted April 9, 2009 Whitewalls = tacky (especially before the paint dries) ;D Link to comment Share on other sites More sharing options...
herald948 Posted April 9, 2009 Share Posted April 9, 2009 KevinR wrote:"Normal" profile tyres are 80 profile, so if there is no profile mentioned, it is 80....I think that's generally true nowadays, but time was when, for example, a 155SR13 might actually have been an "82" or "84" profile.I've never had a problem with 155s on a 3.5" wheel, although Triumph's original radial tire spec. was for the 145. From what I've seen over the years, though, the 145s were a bit "shorter" (smaller overall diameter) than the original 5.20 x 13 Dunlop Gold Seals. Link to comment Share on other sites More sharing options...
alpinemauve Posted April 9, 2009 Share Posted April 9, 2009 I got tired reading this post ::) Link to comment Share on other sites More sharing options...
Marshman 1360 Posted April 9, 2009 Share Posted April 9, 2009 I am confused now guys need new tyres on my 13/60 convertable with original steel wheels that have 145 /13 on at the minute. Can i put 155's on these rims surely they will be more stable ????? Link to comment Share on other sites More sharing options...
Deleted User Posted April 9, 2009 Share Posted April 9, 2009 You need to be certain what width the rims you have are.If they are 3.5" WIDE rims, then 155's may be too wide and the tyres will make the car unstable.For 3.5" wide rims, you really need 145's.If you have 4.5" wide rims, then 155's will be great.You need to check the width of the rims, depending on the age of your car, and what the previous owner might have done, it might have 3.5J rims or it might have 4.5J rims. Link to comment Share on other sites More sharing options...
Raider Posted April 9, 2009 Share Posted April 9, 2009 A photocopy I have of the Triumph section of the Michelin 1971 tech data book says thisHeralds all models (except estate) - 3.5" wheel, original fitment 5.20 13 - then 145SR13. Now you would buy a 145/80R13.I had forgotten that Heralds had 3.5" wheels so if that's what you have then fit the 145/80R13s. Tyres work best when they are fitted to the ideal rim width and again referring to our tech data book a 155/80R13 needs to go on rims of 4" to 5 1/2" with a 4 1/2" rim being the preferred one.Fitting them on a 3 1/2" wide wheel is not recommended.Herald Estate & Vitesse (all) - 4.5" wheels, original fitment 5.60 13, then 155SR13. Now you would buy a 155/80R13.The 80 refers to the aspect ratio and means that the sidewall height is 80% of the nominal section width (not the same as the tread width!).As someone said here, the 155SR13 had an aspect ratio of 82% not 80% as in the 155/80R13. Link to comment Share on other sites More sharing options...
junkuser Posted April 9, 2009 Share Posted April 9, 2009 Thank you for your input Raider.My original query was due to the the Mintylamb comparator showing a considerable difference between OD of 155/80 and 155 "Imperial".(From memory you had to go to 195/80 to get close to that "Imperial" 155 OD and hence rolling circumference and speedo reading.)Is that "Imperial" the 82% ratio tyre you refer to?Is the Mintylamb site accurate? Link to comment Share on other sites More sharing options...
Raider Posted April 10, 2009 Share Posted April 10, 2009 Well my tech data book shows an OD of 588 for a 155R13 and 588 for a 155/80R13!From a ride height point of view the static laden radius is more important (in effect the vertical distance from the centre line of the wheel to the road surface when the tyre is correctly inflated and under load.)The SLR of the 155SR13 is 265mm and the 155/80R13 is 265mm so no difference there either!Rolling circumference should not be calculated from the OD which is a "free" dimension - it should come from the SLR and is diffrent from the 155R13 to the 155/80R13 - 1775v1760mm but that is so close you'd never notice the difference anyway.I'll scan my tech data book and put it up later today ;)If you want to get really into Anorak mode be aware that the OD figure quoted is an ETRTO (European Tyre and Rubber tradeorganisation) figure and is "nominal" which means there's a tolerance on it whereas the SLR and RC figures I quoted are Michelin figures based on actual Michelin tyres fitted to the preferred rim and at the correct tyre pressure for the load imposed.(think) Link to comment Share on other sites More sharing options...
Deleted User Posted April 10, 2009 Share Posted April 10, 2009 Raider wrote:If you want to get really into Anorak mode be aware that the OD figure quoted is an ETRTO (European Tyre and Rubber tradeorganisation) figure and is "nominal" which means there's a tolerance on it whereas the SLR and RC figures I quoted are Michelin figures based on actual Michelin tyres fitted to the preferred rim and at the correct tyre pressure for the load imposed.(think)Well I never knew that Martin was so into his black rubber products (whistle) Link to comment Share on other sites More sharing options...
Raider Posted April 10, 2009 Share Posted April 10, 2009 That is a result of working for Michelin for 17 years ;) Link to comment Share on other sites More sharing options...
Raider Posted April 10, 2009 Share Posted April 10, 2009 As promised - scans of tech data info from 1982 and 1971 ;) Link to comment Share on other sites More sharing options...
junkuser Posted April 10, 2009 Share Posted April 10, 2009 Thank you Martin.Thought the 155 13s I have may have been the "Imperial" on Mintylamb comparator so would cause further over reading of the speedo which is already exagerating due to the change from the bias plys.Could that "Imperial" just be a theoretical size and in fact all 155 13s were built to 82% rather than 100%?"Rolling circumference" is an old term we used in the 50s and was a rough guide as to the progressing resulting from one revolution at recommended pressure, rim width and load.I still use the term "Bias Ply" rather than the more recent "Cross Ply" as the plies were set out like material cut on the bias. Link to comment Share on other sites More sharing options...
Raider Posted April 10, 2009 Share Posted April 10, 2009 I am fairly confident that all 155R13s are 82% aspect ratio.Having said that I was only a boy in the 60s so I can't be sure.Interestingly my dad worked in a tyre remoulder pre WW2, trained ground crew in the RAF on how to look after aircraft tyres in WW2 and then owned a tyre retail business in the late 50s/early 60s so he may have had an opinion.Looking at the Montylamb site tho (James -a forum and CT member) I think the "Imperial" choice there will be really for cross plies and you can't actually choose those sizes! So, yes I think it's a theoretical size as you say.I agree completely with your definition of "Rolling Circumference" but it's a term we still use now (although I am in the Ag tyrworld in Michelin at the moment). Link to comment Share on other sites More sharing options...
.thumb.jpeg.b15b81ef10abeea1c3039ae03c4a9f3a.jpeg)
Recommended Posts
Archived
This topic is now archived and is closed to further replies.