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Help with tyre selection


Chris Norman

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I am quite new to se7en ownership and need some help in selecting tyres for my 1.4SS.

 

Currently has AO21's fitted - 205/60*13 on the rear and 185/70*13 on the front. Both front and rear are almost worm out so need to be replaced soon.

 

I have read through several threads on BC and was thinking of replacing with AO48's but notice from George Polley's site that 48's are not available in 185/70*13 (I was going to replace with the same sizes). The 21's seem OK to me (no real experience of different makes etc) but I would like to try a beginners track day at some point and BC appears to indicate 48's may be slightly better than 21's for the track, whilst still being very good for the road, which is where the vast majority of my miles will be done.

 

Why would someone put 70 profile on the front and 60 profile on the back? Is this to do with wider tyres at the back or just ride heights?

 

Should I just replace with the same to try and keep the same setup? Going the 48 route means (I think)putting 60 profile on the front - but lowering the car, which is low anyway!

 

Any help/words of wisdom will be gratefully received.

 

Thankyou

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If you switch to 185/60 at the front you'll drop the ride height by 18.5mm. Does your car have adjustable platforms? If not you might be putting your sump at risk....

 

Cheers

 

Tom

 

FH54WLX - only the car supports ManU, honest!

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Chris, I guess the reason for 70 profile and 60 at the back is because a 185/70 has roughly the same diameter as 205/60 so would maintain the same ride height front to back. Conventional wisdom seems to be that you wouldn't need 205's on the back, for the power levels you have, as the car would be over tyred.

 

I haven't tried A021's so I can't comment but A048's I have tried and are good (and they look better than A021's). I have 185/60 *13 all round on my car at the moment and it is a nice setup but I only really drive the car in dry conditions so can't comment on A048's wet weather capability. I would have thought 185/60 A048's all round would be fine for your car but I guess it depends on how low the car is already.

 

Have fun.

 

Graham.

 

R7 GPK

Superlight #85

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Graham thanks for the comments re 48's and the 205's. Maybe I should put a more powerful engine in 😬 😬 😬

 

I will measure ground clearance and look at the adjustable platforms with a view to going the 48 185/60*13 route. I guess I should also check the width of the rear rims to make sure they will take the narrower tyre. (You are right the 48's look very nice, what a tart I am 😳)

 

 

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have a look at Angus&Tessa site http://www.mycaterham.com/66828/42806.html.

 

All new owners - like me 1.5 yers ago - (I posted a thread like "are my Michelin Pilots going to kill me?" 😬) ask about tyres.

 

Angus patiently explaimed to me the pros/cons of 21's 32's & 48's

 

Oh and don't forget that if you go for 185/60/13 all round, your speedo reading will be even more wrong! Lots of people here don't care, I personnaly do

 

Ground clearance is really critical for me as I don't have adjustable platforms and I live in London (read - huuuuge speed bumps every 10 yards)

 

Edited by - Miura on 3 Mar 2006 16:26:54

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FWIW, I'm currently changing from Avon CR322 to yoko A021Rs, because I'm less confident about the wet weather behaviour of the A048s. Anything's got to be better than CR322s though... Plus sticking to 021s means I can keep my 185/70 and avoid having to mess with the spring platforms.

 

You may also find the ride more harsh on 185/60 tyres. I'm touring France on tillet seats so for me this was also a consideration.

 

 

Cheers

 

Tom

 

FH54WLX - only the car supports ManU, honest!

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Hi Chris

 

Welcome to the madness that is 7 ownership. Isn't it great to know that you can pose a question & get several answers all within a period of a few nano seconds!

 

Angus & Tesa's site is always worth a visit & their treatise on tyres is well worth a read.

 

You have a 1.4SS which is where I started. You've probably worked out that 21's in 70 profile are dirt cheap from G Polley & I would put 185/70/13 tyres on all round for road use regardless of the power output. As pointed out you do not need 205 wide tyres at the back. 21's also have a habit of lasting longer than 48's & 32's but can cut up a bit on hot track days.

 

However as each tyre costs less than the average tin-top to fill with petrol............................ consider it a track day consumable. If the track day bug bites, & sometimes it can leaving huge scars on your wallet, then invest in "better" tyres.

 

Mick

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Miura/Mick Looked at Angus and Tessa's site very helpful indeed, and along with all the feedback here is quite amazing. Tom I hear what you are saying about driving in the wet.

 

Just got of the garage and have tried to measue the rims by poking tape through spokes and taking best measurement. Rears measure at about 8" and fronts 7" which seem quite wide when looking at the George Polley tyre measurements/rim sizes so I am probably over measuring. Will take a wheel off tomorrow to see if sizes are marked anywhere.

 

Mick looked at the prices this afternoon wow - a set of 4 AO21's comes in around £100 cheaper than AO48's *eek*

 

Thankyou to everyone who has replied, BC is prooving to be a very important part of Caterham ownership. *thumbup* *thumbup* *thumbup* *thumbup* *thumbup*

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Size of the rims will probably be stamped either on the face of the hub, where it meets the wheel hub, or on the inside of the rim.

 

If you do have wider rear rims than front, I don't think you'd be able to switch to 185/70 all round, they might be overstretched on the rim.

 

My real worry with 048s in the wet was that, as they start with shallower tread than normal, by the end of a long trip they might be a bit tricky. I'm hoping to do 2500-3000 miles in france this summer, which would be a fair chunk of the life of 48s, and the way the rain can run across the Autoroute near Calais.....

 

 

Cheers

 

Tom

 

FH54WLX - only the car supports ManU, honest!

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