max allowable front tyre size

[Fulvia-hf]

Does any one know what the maximum allowable tyre width is for the front wheels in the S1 early S2 body without having to change the wheel arch?

I would like to fit 175/70R13 on 6.5" rims.

Cheers,
William

[4129R]

For 175/70 tyres I would not use wider than 5.5" wheels.

[BDA]

 

Here’s a calculator. Enter the wheel width and it gives you minimum and recommended tire section width. https://tiregrades.com/tire-anatomy/tire-size/min-max-tire-size-for-rim-width/

[Kendo]

And remember that different manufacturers’ tires will have slightly different dimensions. So one 175 might work while another wouldn’t. Maybe your tire vendor would allow test fits?

[jbcollier]

Europas are individually laid up.  Every one is a little different.  175/70r13s work well for me.  Check carefully on yours at full lock and full compression.

[RonPNW]

I have 205/60-13 with 6" rims on my 70 S2.
They will definitely rub on the rear inside of the wheel well and the top center of the wheel arch.
They need roughly 1/2 inch additional clearance in both areas.
They only rub when turning, worst is turning and entering a driveway.
Enlarging the wheel arch as we speak.

They don't rub in the back.

Ron

[Clifton]

I have 205/60-13 with 6" rims on my 70 S2.
They will definitely rub on the rear inside of the wheel well and the top center of the wheel arch.
They need roughly 1/2 inch additional clearance in both areas.
They only rub when turning, worst is turning and entering a driveway.
Enlarging the wheel arch as we speak.

They don't rub in the back.

Ron

Mine too. I used some pvc for spacers that clip on the rack to limit turning and cut out the rear inner and re glassed it.

[Fulvia-hf]

At the moment I have a set of Avon ACB9 Formula Ford tyres fitted but they are cross ply and strict competition tyres. I have 6.5" front wheels and 8.5" rear wheels.
It seemed that no manufacturer makes suitable road tyres for these wide rims. However i came across a Caterham Forum where the Caterham superlight 500 seems to have 175 and 205 on respectively 6" and 8" wide 13" rims. The superlight is less than 100Kg lighter than the S1. The odd thing is that no manufacturer allows a 175 on a 6" rim or a 205 on a 8" rim but Caterham seems to have legalized this stretch.

[Clifton]

At the moment I have a set of Avon ACB9 Formula Ford tyres fitted but they are cross ply and strict competition tyres. I have 6.5" front wheels and 8.5" rear wheels.
It seemed that no manufacturer makes suitable road tyres for these wide rims. However i came across a Caterham Forum where the Caterham superlight 500 seems to have 175 and 205 on respectively 6" and 8" wide 13" rims. The superlight is less than 100Kg lighter than the S1. The odd thing is that no manufacturer allows a 175 on a 6" rim or a 205 on a 8" rim but Caterham seems to have legalized this stretch.

Nankang has a lot of 13" sizes in their AR-1 https://philstireservice.com/product/nankang-ar-1/ as does Toyo in the R888Rhttps://philstireservice.com/product/toyo-proxes-r888r/. Everyone that wants optimal tire/wheel width runs a 205 on an 8" wide wheel. GRM has done comparison testing as have Miata track guys, they mostly run 8"/205 or 9"/225.  Tire manufacturers spec a min-max wheel size but it does not mean their max width listed is really the max or fastest. In the US, Discount will not mount past the spec'd max width though but go to any autoxcross or track and everyone allowed by class, runs wider wheels.

[Fulvia-hf]

I would like to see a modern radial 205/60R13 tyre on my 8,5j rim to see how stretched they look. I would like to know if the side wall protrudes beyond the rim lip like the ACB9's. A look which I really love. Those tyres with a thread pattern very faithfully replicating the famous Dunlop Racing tyres look amazing under the debumpered type 47 body. Unfortunately they are not road legal and, as they are bias ply tyres, are probably very poor outside a track anyway. https://www.avontyres.com/en-gb/tyres/acb9

[Clifton]

Most performance tires (200 treadwear and under) are considered summer tires. They perform great on the street except in wet and cold weather. Some say not to use under xx temperature.

GRM tested a A052 205/50-15 on a 15x9. https://grassrootsmotorsports.com/articles/200tw-showdown/

A thread with some pics of 205's on 9"'s https://www.miataturbo.net/wheels-tires-78/another-15x9-225vs205-tire-thread-92211/

13" 205/60-13 R888R on a 13x8 https://forum.wscc.co.uk/forum/topic/139987-13-x-8-cxrs-with-toyo-r888r-2056013/

205/60/13 R888s on 8 https://www.reddit.com/r/AE86/comments/udaghx/fat_meats_on_fake_wheels_2056013_r888s_on_8j/

[Fulvia-hf]

Does anyone has experience with crossply racing tyres on the road?

[DAllen]

I would like to see a modern radial 205/60R13 tyre on my 8,5j rim to see how stretched they look. I would like to know if the side wall protrudes beyond the rim lip like the ACB9's. A look which I really love. Those tyres with a thread pattern very faithfully replicating the famous Dunlop Racing tyres look amazing under the debumpered type 47 body. Unfortunately they are not road legal and, as they are bias ply tyres, are probably very poor outside a track anyway. https://www.avontyres.com/en-gb/tyres/acb9

Consider putting up pics of your rear suspension?  What all do you have there?

[Fulvia-hf]

Maybe it would be better to start a new thread on this subject. My suspension is 'slightly' modified to accomodate 8.5J rims in the standard S1 wheel housing.