Tyres for Mk1 17" straights

[dave23572]

Looking for some advice here:-
Sorry if this has been covered before, but after reading some threads I thought it best to ask specific question:-

My (not lowered) Mk1 180 car is mainly road use but will be doing two or three trackdays per year.

Looking for a good value but good performing tyre choice.

What sizes are people running on Mk1 17" straights?
I was considering changing from the OE 205/45/17 to 215/40/17.
I read they're cheaper as it's a more common size, but also the lower profile may help steering response.

But:-
What about wheelarch rubbing?
Will they look "small" on a non lowered 180?
Will the ride be much worse?
Will non OE tyre sizes affect speedo accuracy?

[talkingcars]

Personally I'd stick to O/E on the mk1, if it was a mk2 I'd go for the 215/40/17 as the wheels are slightly wider as 7.5J, mk1 is 7J.

Using http://www.etyres.co.uk/tyre-size-calculator shows that the closeset to the O/E spec is 225/40/17.

I've just fitted 225/35/18 tyres on my new wheels, there is no rubbing.

[dave23572]

Do you think the sidewalls would be bit pushed with 215/40/17's on 7J Mk1 straights?

Using that calculator the overall diameter is slightly less with 215/40/17 when compared to the OE profile, so wheel arch rubbing shouldn't be an issue.
But it will affect gearing slightly, but hard to say by how much.
Obviously it'll be revving slightly higher for a given speed (real rather than indicated). Also the speedo accuracy will be affected, again hard to say how badly.

It's very tempting to for to 215/40/17, because I'm looking for more responsive steering, but worried about the trade offs.

[henocsr]

I toyed with different tyre sizes on my MK1 with striaghts. But stayed with the standard 205/45 17. I got Avon zz5s, they are quite affordable, have great grip and have the added bonus of having small z's around the outer side wall. Look like they are an OE tyre for the designed for the MG Z car range

[Lukeus101]

id say the same 205 45 17. Falkens have always been a good all rounder for me and kate :)

[MG ZS STE]

Can't speak for mk1 180 straights but, on my mk2 180 11 spokes I went from 205 45 17 to 215 40 17 and the difference is very noticeable. You have more tread on the road and less tire wall to absorb road noise, so it will increase. But, I did find late braking improved and quick corners felt like the tires were less squirmy.

[dave23572]

Can't speak for mk1 180 straights but, on my mk2 180 11 spokes I went from 205 45 17 to 215 40 17 and the difference is very noticeable. You have more tread on the road and less tire wall to absorb road noise, so it will increase. But, I did find late braking improved and quick corners felt like the tires were less squirmy.


Did the steering response improve as well?
Did it improve the turn-in?

Did your speedo start to over-read more than normal?

[Mark S]

the 205 should be a better tyre on a mk2 rim than a 215.

I know of some 205 tyres that are wider than other manufacturer's 215's.

Different sidewall stiffness can give a different feel to tyres, noise can vary so much between tyres/makes also.

What one person sees as a good move may not be the same for someone who follows suit in size, but goes from and to different brands of tyre.


All of your questions are relative to each specific tyre (make/model/tyre/construction/compound, even which plant/factory it was made in)

Personally, I would stick to the 205/45 size, but think and choose very carefully the tyre itself.
A good allrounder could be a toyo tr1, used in racing as a wet tyre, whilst it could get chewed up by some (a well setup race car pulling some serious cornering force) race cars in the dry, on a fairly boggo ZS it should be perfect in the dry too.

[dave23572]

Trouble is, sidewall stiffness isn't something that's measured or quoted.
Only people's impressions, which are also subjective.

Or are they any tyres that are known for having stiffer sidewalls?


Choosing tyres if you're quite particular is certainly baffling.

[p_b82]

I know that it is all subjective, but I didn't like the T1R's on the derv, did not give as good a feel as the BFGoodriches I was using - but I can't seem to get them anymore :(

I got them 'cheap' but I've got pirellis on the front and I have to say they are amazing in wet and dry - by far the best tyre I have used in 104K miles. But normally I wouldn't have gone near them due to the price!

WRT to the lower profile, I'd personally avoid it myself as you do want that little bit of squidge in the tyre to help out over the bumps, as our roads are not getting any better as time goes on!

And also typically the higher the load rating the stiffer the sidewalls, the derv I know should have 88's which is a good ton over the actual vehicle weight, but I know it is not that cut and dried as to the ratings, as braking&cornering forces and things like that seriously alter the load at any given moment

[Mark S]

I really wouldn't get too hung up about it all, you say its a road car that does a few track days, for me, just stick with a nice tyre on the original size and get the pressures right, every ones got such differing opinions as to what is good and what is not, but your not after the last 10th and your not going to spend money testing tyres and getting them in the zone for the car.
It is amazing to hear how many people bang on about tyres at race circuits yet most of them have never gone testing for tyre data, they just guess (may as well pull numbers out of the air) its just talk and hot air, similar to the nonsense you overhear down the local!
Tyres are really complicated and so much more than just a black bit of rubber with a name and a so-called size, few people really understand them, that's why I say, don't get too hung up on it, its just a road car!