Tire size question

[rjbaren]

I am nearly ready to buy tires for my Cosmic wheels.  I was going to buy Toyo Proxes 205 60 13s in the rear and 185 60 13s in the front.  I went to a local British car shop that races a Europa and they recommend I go with 195 50 13s all around.
Any comments?

[cazman]

With a race set up, it is easy to adjust the suspension to use non-staggered. And tires can be rotated to extend life. I have always thought that with factory suspension, one should stay as close to the factory sizes as possible.

[TurboFource]

Not sure that size is available here?

[BDA]

I think people have their own ideas about tire size. Since you have decided to stay with 13” wheels your choices are limited. If you’re using the stock speedo, you’ll probably impart some error. You can get a sense of that error by using this website (https://tire-calc.com/). That error can be corrected and then we aren’t sure of the original accuracy of this speedo.

I chose 195/50-15 in the front and 205/50-15 in the rear. I wanted wider wheels and the 205/50-13 has a very similar in diameter to the original 185/70-13 tires. 195/50-15 front tires sort of fell out of that decision. Another motivation was the hope that tires would be more readily available in the 15” size than the 13” size. Early on, I mentioned my tire choices to Richard at Banks. He didn’t say much about them but I got the distinct impression he thought they wider than useful.

I’ve read of people who swear by 185/70-13 front and rear so in spite of the original Lotus design, a non-staggered arrangement may work just fine. But then you might wonder why Lotus used the staggered arrangement in the first place…

That shop that races Europas may have the right idea. And then it matters just how far you expect to push your car and how sensitive you are to those changes.

[Fotog]

This has been discussed A LOT both here and on another forum.  I suggest you take your time deciding, and use the search engines to find the discussions.

If you're not aware, this one may be of help:
"KnowledgeBase" https://www.prevanders.net/kb2.html

Vince

[jbcollier]

The original spec was the same size tire all round.  For the later TC models, aluminium wheels with a different size front to rear was an option (standard only with the JPS package).

Generally speaking, fitting larger tires to the rear increases a car's tendency to understeer.  This is considered "safer" for the average driver.  This is because a car that tends to oversteer leads ordinary people to lift off the throttle which leads to even more oversteer.  It is speculated that Shakespeare drove a Porsche which led to his famous stage direction "exit facing backwards, pursued by a bear".

[Clifton]

I am nearly ready to buy tires for my Cosmic wheels.  I was going to buy Toyo Proxes 205 60 13s in the rear and 185 60 13s in the front.  I went to a local British car shop that races a Europa and they recommend I go with 195 50 13s all around.
Any comments?

  I'll ask this. What decent mid engine car other than a low cost, steel wheeled Europa uses the same width front and rear? Lotus made a cheap mid engine sporty car. The 47 was built to be competitive, what size does it run F/R?

People run equal width on lower powered 50/50 weight cars. Miata's for example autocross or road coarse and they use the same width, they are neutral and fast.

You said Proxes, I assume RA1's? If so you must be planning on pushing it. Yes, you can tune the balance with bars and springs to a point but the load is the load and there is more load on the rear.

More weight on that end, more tire. For a casual street driver, it doesn't matter.

[cazman]

With a race set up, it is easy to adjust the suspension to use non-staggered. And tires can be rotated to extend life. I have always thought that with factory suspension, one should stay as close to the factory sizes as possible.

Sorry what I meant by size was overall dimensions - diameter and width. Many ways to get close, like going to 15" if needed. In my experience with another mid-engine car is that snap oversteer can be a factor, hence why many manufacturers go with the larger width in the rear. As Clifton said, it tends to promote understeer which keeps you further away from snap oversteer. 

[SwiftDB4]

I am nearly ready to buy tires for my Cosmic wheels.  I was going to buy Toyo Proxes 205 60 13s in the rear and 185 60 13s in the front.  I went to a local British car shop that races a Europa and they recommend I go with 195 50 13s all around.
Any comments?

If you like the look of a wider 205 tire go for it!
I run 235/50/13 rear and 215/50/13 front.. Won't fit under a stock body, but the handling is great.

[TurboFource]

Swift,
Are you running Vitour Formulas?

[SwiftDB4]

Swift,
Are you running Vitour Formulas?

Yes. I'm always skeptical about Chinese tires, but am pleasantly surprised about the quality.

[rjbaren]

I looked again at the Tire Rack offerings, and I see nothing available in 195 50 13.  The only thing available from Tire rack in the 205 and 185 is Hoosier, and Toyo R888R.  Phil's Tire Service also has Nanking available.  John Brown Wheel in England has more choices, but the shipping is a bit expensive.  I probably should have looked at the options before I asked.  I am not yet ready for 14" or 15"wheels since I recently bought the 13" Cosmics.  But who knows what the future holds?
Thank you for the replies.

[TurboFource]

Swift,
Are their pics of your car on this site?

[SwiftDB4]

Yes there are. But here's one:
The tires in the photo are not current, but are 215/50/13 front and rear.

[SwiftDB4]

I looked again at the Tire Rack offerings, and I see nothing available in 195 50 13.  The only thing available from Tire rack in the 205 and 185 is Hoosier, and Toyo R888R.  Phil's Tire Service also has Nanking available.  John Brown Wheel in England has more choices, but the shipping is a bit expensive.  I probably should have looked at the options before I asked.  I am not yet ready for 14" or 15"wheels since I recently bought the 13" Cosmics.  But who knows what the future holds?
Thank you for the replies.

Vitour makes a 195/55/13 tire. They are Chinese, but I've found the quality better than expected for a street tire.  You're looking at a lot of options like trackday ones so depends on what you're going to use them for.