Keith7 Posted February 3, 2015 Share Posted February 3, 2015 HiLast week I was lucky enough to place an order for my first Caterham - a new 180 bhp Duratec in Supersport spec, to use both on the road (Cotswolds and Mid Wales) and some track days.I had thought 15" wheels would be the best compromise because of the state of UK roads, which was the view of an owner with same car I met a few weeks ago.However Caterham say 13"s are better as they break away more progressively and the higher profile tyres compensate for the smaller diameter wheels.Tyres would be 175/55/13" front on 6" rims and 205/55/13" rear on 8" rims, versus 195/45/15" on 7" rims all round.Does anyone have experience of both or can offer any advice please?Keith Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted February 3, 2015 Member Share Posted February 3, 2015 WelcomeAny views on which tyres you'd like?What ground clearance are you aiming for? Very low?Jonathan Link to comment Share on other sites More sharing options...
Keith7 Posted February 3, 2015 Author Share Posted February 3, 2015 JonathanThe car will come with Avon ZZS tyres. I do not want to lower the car from the standard spec although I need lowered floors simply to give me kneeroom around the steering wheelKeith Link to comment Share on other sites More sharing options...
Alan Bowler Posted February 3, 2015 Share Posted February 3, 2015 13" definitely. Better handling, cheaper tyres, good choice of sticky tyres. Smaller diameter (depending on profile) so marginally lower geared = better acceleration too. I only went to 15s as the preferred MSA List 1A tyres were not available in 13". Happy to go back to 13s when I wear the tyres out.The 15s perhaps look better and fill the arches more, but you bought the car to drive, not to look at, right? Link to comment Share on other sites More sharing options...
FramerateUK Posted February 3, 2015 Share Posted February 3, 2015 Mine came with 15" wheels, and I'm now on the small 13x6 wheels all round.The ride height is a bit lower, but apart from a few particularly nasty speed bumps (usually, the tall but narrow kind) I've had no issues.The handling is definately more predictable on the small wheels. As has been said, you can feel the slip approaching before whe wheel actually looses grip. Link to comment Share on other sites More sharing options...
Mavic82 Posted February 3, 2015 Share Posted February 3, 2015 Congrats on the new purchase.we shall now begin the thread of folk disagreeing :-) . Personally I would go for the 15", the car was never designed for small wheels and lowish profile tyres. Whilst some may say the 13" are more progressive I would say there is little difference if you have the car set up with appropriate spring rates, roll bars, dampers etc. they just need different settings.the larger wheel and lower profile tyres have several advantages including less tyre distortion.choose which ever you like, it's your car and you can get the car to work equally well on both. Pone key thing to consider is what tyres are available for the rims size you choose. 14" and 16" have very small selections available. Link to comment Share on other sites More sharing options...
RS2000 Posted February 3, 2015 Share Posted February 3, 2015 Out of interest, what wheel / tyre size combo was the car designed for? Link to comment Share on other sites More sharing options...
Slipper man Posted February 3, 2015 Share Posted February 3, 2015 I can't agree that the car was designed for 15 inch wheels - they are a relatively new innovation. I have tried most wheel tyre combos and 13 inch is the way to go. The car feels much better and as Caterham pointed out, with higher profile tyres, the overall diameter (and therefore ride height) need not change. When I ordered my first Caterham I went through the same debate, ignored the advice and ended up with the then fashionable 16 inch wheels. Big (and expensive) mistake. 13 inch wheels transformed the car for the better. Not just in handling etc, but in ride quality and steering feel too Link to comment Share on other sites More sharing options...
BBL Posted February 4, 2015 Share Posted February 4, 2015 Tyres would be 175/55/13" front on 6" rims and 205/55/13" rear on 8" rims, versus 195/45/15" on 7" rims all round. Plugging in your numbers above on willtheyfit.com yields the following:Front: 195/45-16 diameter is 556.5mm 175/55-13 diameter is 522.7mm Difference: 33.8mm, which equates to a 16.9mm lower ride height in the front on the 13s.Rear: 195/45-16 diameter is 556.5mm (again!) 205/55-13 diameter is 555.7mm Difference: 0.8mm, which equates to a 0.4mm lower ride height in the rear on the 13s.Ride height is easily adjusted with the collars on the dampers. You will want to specify your car to have the dampers to have the ride height adjusting collars (or whatever the trade name for these might be).When I went through this decision, I read posts with lots of opinions on either side. It seemed to me that generally, those who went with larger wheels (14", 15", 16") did so primarily for aesthetic reasons, and those who went with the smaller wheels (13") did so primarily for performance reasons. On my own 7, I have only ever known 13s, so my opinion will be of little value here.Best of luck, sir.-Sean Link to comment Share on other sites More sharing options...
Keith7 Posted February 4, 2015 Author Share Posted February 4, 2015 A very interesting question. For the last couple of years Caterham were selling it with 13x6 wheels front and rear with 13x8 rears as an option, or the 15" wheels as another option. They have now swapped and are making the 15" wheels standard with the 13x6's as a no cost option or with the 13x8's rear added for £200. I suspect the switch is to do with showroom appeal but could be wrong. The tyres sizes throughout are the same as in my orginal post. Link to comment Share on other sites More sharing options...
Keith7 Posted February 4, 2015 Author Share Posted February 4, 2015 SeanThank you for the willtheyfit.com website address - very helpful. I think your comment about aesthetics versus performance is evident in some of the other posts.Keith Link to comment Share on other sites More sharing options...
Nigel Riches Posted February 5, 2015 Share Posted February 5, 2015 When I contacted Caterham cars a long time ago, about putting sexy big wheels and wraith like tyres on my 1982 car the answer was, "no, don't do it" , the tyres are part of the suspension "system", and the chassis in my car isn't designed to be able to withstand the extra loading which can be generated by low profile sticky tyres, leading to cracked brazed joints, and possibly some visiting the roadside scenery, not good. Ok, later chassis where modified to take account of the extra power available and the improvement in tyre construction. So I still have the 13" wheels, ok, tyres have moved on to A021's, (better than Goodyear G800, or Yoko S707), the ride compliance is, ok, not limo, for sure. Motor vehicles are a complex system of interacting components, and changing one part will interact with others, not always for the better, everything here is a compromise, so, there are wheel /tyre/suspension /chassis combinations that work good on track, and different set ups for road use.You need to be able to accept that a car predominantly used for road will be compromised on track, but there are a lot of "things, stuff, set-ups" that can assist you, the Lotus 7 design is an ancient design , however it is still looked upon as the tip of purist motoring. What ever you do, have fun, plenty of people here available for advice, and some facetious comments, don't take them personally. All the best. Regards, Nigel. Link to comment Share on other sites More sharing options...
Keith7 Posted February 5, 2015 Author Share Posted February 5, 2015 Thank you everyone for so much feedback. It has been a great welcome to the club and I very much appreciate it. It is also reassuring to know that plenty of you have been through this debate!What shows through in the posts is that all of you who have tried both sizes definitely favour 13" wheels, so I have decided that this is the way I am going to go. Once again, many thanks for the friendly advice. Roll on July when I take delivery!Keith Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted February 5, 2015 Member Share Posted February 5, 2015 :-)What are you going to do until July?Jonathan (14" and about to fit A021Rs) Link to comment Share on other sites More sharing options...
CharlesElliott Posted February 5, 2015 Share Posted February 5, 2015 Welcome.13" without question! Link to comment Share on other sites More sharing options...
SteG Posted February 5, 2015 Share Posted February 5, 2015 I'm buggered then. I've got 14" wheels!!! Link to comment Share on other sites More sharing options...
Mavic82 Posted February 5, 2015 Share Posted February 5, 2015 Nothing wrong with 13" wheels with deep section tyres to keep the rolling rad right. As long as you like squishy non precise feel and a comfy ride.13" wheels with low profiles are light but reduce ground clearance and dont have the 'suspension' effect mentionedYou just need to set the car accordingly you cant just change wheel/tyre size and expect nothing else to change.16" with low profiles look great, feel great but are a bit harsh, you cant get many tyres suitable and are heavy15" are the sweet spot between the bunch, have the right radius and with the right set up are pregressive grippy and dont flex around like mush.I just dont get this 'you must fit 13" wheels' urban myth. But as I said before fit what you want because you like it thats the key. Link to comment Share on other sites More sharing options...
Smithy77 Posted February 5, 2015 Share Posted February 5, 2015 Mavic, if that is the case, why have F1 cars used 13s with huge profile tyres for years?? Not for the comfort presumably... Link to comment Share on other sites More sharing options...
Mort Posted February 5, 2015 Share Posted February 5, 2015 185/70 x13 for me. A much nicer ride on our 3rd world roads. Link to comment Share on other sites More sharing options...
twincamtim Posted February 5, 2015 Share Posted February 5, 2015 Does anyone know if George Polley has any E marked Yokohama AO21's left?? Link to comment Share on other sites More sharing options...
Mavic82 Posted February 6, 2015 Share Posted February 6, 2015 F1 remain with13" as a legacy, that is the point. They are designed with little and poor suspension characteristics and make use of the tyre to provide suspension. They are engineered around the tyre because of the tyre. They would need a radical change to make use of a different configuration which would give them packaging issues etc and certainly rebate the gridif they were so great why would not see all race cars set up so, lemans, WTC, etc etc etc. Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted February 6, 2015 Member Share Posted February 6, 2015 Does anyone know if George Polley has any E marked Yokohama AO21's left??I bought a set from them just before Christmas: info@polleymotorsport.co.ukJonathan Link to comment Share on other sites More sharing options...
7 wonders of the world Posted February 6, 2015 Share Posted February 6, 2015 A few things to consider here:Generally speaking 13" will offer reduced rotational mass and reduced unsprung weight, depending on size and profile gound clearence can be compromised though this depends on your intended useage.13" in taller profiles do in effect act as an undamped air spring, its also true that the additional sidewall height will offer more tyre compliance on 'normal' roads, 45 profiles can offer better peformance on smooth tracks and offer more brake clearence too.The choice of tyre greatly affects the characteristics in both sizes, tintop tyres have additional carcass layers in order to meet the higher load rating required for tintops, therefore their unit wieght is higher and their complicance is compromised.Tyres designed for the application ie CR500 etc do offer improvements in both these areas. You also need to consider the suspension geometry used (base settings) and how this changes with the travel and the affect this has on the tyre contact patch. Link to comment Share on other sites More sharing options...
martyn Posted February 6, 2015 Share Posted February 6, 2015 People often say that a higher profile tyre side-wall will be more progressive as it breaks away and provide more feedback to the driver. Both of these things are true in my opinion, but most people fail to explain the reason why..A higher profile tyre side-wall will achieve a greater slip-angle (essentially flex) before the tyre actually breaks away. Feeling this increasing slip angle through the steering and chassis is an important feedback indicator. It allows a driver to judge the load levels through the tyres and accurately detect the point of any impending break-away. Link to comment Share on other sites More sharing options...
twincamtim Posted February 6, 2015 Share Posted February 6, 2015 George Polley still have E marked AO21's for sale - 185x70R13's at £50 +VAT each!No idea what stock is left, sorry. Contact them on: 01354 688111 Link to comment Share on other sites More sharing options...
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