I have been looking at 7 type cars for a while and notice that most people are using road derived 7” wheels and tyres. is this purely for cost reasons?
I have also seen a few hill climbers using 10.5” and 8.5” wheels, does the extra rubber make any difference on a 7?

Opinions on the web seem to vary greatly on the subject of increasing tyre width, some are for and some are against, please discuss!

You'll find that people use even narrower tyres than 7", particularly at the front. The problem with wider tyres is that with such a light car, once you get a bit of rain the car will aquaplane very easily. I think you'd be better off sticking to narrower tyres, this will give a better car overall.

Pete

im using 7" wide 15" dia wheels purely cos they were there. i dont intend going any wider than 195 tyres. If poss i would have gone narrower on the wheels. 13" wheels with 185 rubber seem to be popular.

Is there any arguement for choosing narrow high profile tyres - say 165 70
Would this give better (or more enjoyable) handling at the expense of less grip ?

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Who cares about the wheels, I want that BDA.

I think its mostly for cosmetic reasons that people go for wide wheels, have a look at the RCB77 website for some extreme wide tyres

If you only plan to race the thing on nice smooth tracks and always in the dry, the wider the better! Ain't some guy on here using formula 1 wheels and tyres?

I'll stick with me 195/50 15s

Liam

mine has 13x5.5 at the front, 7 at the rear with 205 tyres. Thats more than enough grip for a 1.6 pinto!

Its the age old debate about how the car breaks away when it runs out of grip. Make your own mind up!

low profile tyres give better tyre control - they twist, stretch and roll less. This gives better turn in adn better response to small steering movements.

High profile tyres are more quashy and give a better ride.

Both tyres (for the same width and rolling circumference) give the same amount of "grip" because they have the same area of rubber touching the road.

I am told that high profile tyres loose their grip progressivley and very low profile tyres hold on longer but then let go more quickly.

It all depends on the planned use of the car. My U.S. autocross car uses 8" front and 10" rear tires (slicks) and still has a good bit of overstear (190hp & 1250lb). I have played with the idea of going up to Formula Atlantic sized tires, 9" front and 14" rear, but for autocrossing a narrow car is generally better (to fit between the cones).

I have 13" x 5.5" wheels with 185/70 tyres. Smooth ride, and an easy and predictable tail slide when I get silly/careless.

David