Tyre gurus' advice on SE tyres please

[davekmoore]

My SE's PP2s are about ready to be changed. The car has enough power to handle a decent increase in gearing. The driver has enough lack of ability to appreciate wider tyres to give the rims the protection competely missing with the current 205-40-70s.

So 215-45s apparently gear it up about 5%, but are they wide enough to protect the rims?

Apart from extra weight are there any downsides to going to 215s or wider still (225s and 235s seem also to be readily available)?

I realise going from 40s to 45s will lose some sidewall stiffness but I don't need ultimate handling or grip and instead quite like the idea of maybe a bit more comfort. For the same reasons I don't need extra grippy compounds etc. Nor I am a brand snob.

Any recommendations on sizes, brand etc?

Thanks in advance for any advice.

[Hammer]

There are tyres designed with "Rim Guard". So if protecting your rim is the main reason you're going slightly wide, it would be better to stick to the same size tyre and just choose a tyre that incorporate this design.

An example are the tyres I got for my stock NA. When I replaced the Yokohamas with Potenza Adrenalins, even though they are the same size, the sidewalls of the Adrenalins stick out further from the rims, thus adding some protection.

Falken FK-452s also have this design. I'm sure a lot of other brands do too.

[davekmoore]

There are tyres designed with "Rim Guard". So if protecting your rim is the main reason you're going slightly wide, it would be better to stick to the same size tyre and just choose a tyre that incorporate this design.

An example are the tyres I got for my stock NA. When I replaced the Yokohamas with Potenza Adrenalins, even though they are the same size, the sidewalls of the Adrenalins stick out further from the rims, thus adding some protection.

Falken FK-452s also have this design. I'm sure a lot of other brands do too.

Thanks Hammer.

The priorities are 1) full rim protection, 2) increase in gearing, 3) comfort, 4) grip. Value for money is also in there somewhere between 1 and 4!

I know an MX5 purist would rightly disagree with the order of these but despite all its mods this car is a daily driver so the first three would just make it more civilised.

These cars seem to have way more grip than I need even on worn tyres, that grippy compounds just don't seem necessary, especially if going wider.

Going up in width and profile seems to increase the choice of tyres and decrease prices, perhaps because the larger sizes also go on mass market cars such as Falcadores.

[MINX]

Dave,
I would recommend against 215/45 on std rims and std suspension.
Although i think you have other suspension.
The different 'gearing' of 215/45 throws out your speedo the wrong way noticeably, so you have to drive under the posted speed all the time. I found this annoying. And you wont notice any change in gear shift points.
On std suspension they also rub on front guard liners on dip, bumps and hard turning.
So you may have to wind up your height a bit.

I find 215/40s perfect. Also going wider to achieve more grip is a very highly debated topic, ie contact patch size

I am on my second set of BFG G-Force Sport 215/40/17 and am very happy with them. At $184 each fitted, cant go wrong.
They have a small rim protection bead.

Stu

[wun911]

Rim protection isn't woth the extra rotational mass, you can still get curb rash with the rim protector it just doesnt stick out enough.

[sliq]

i'm very interested in this rim protector. will have to look into it when i get new rubbers this year.

[davekmoore]

i'm very interested in this rim protector. will have to look into it when i get new rubbers this year.

My experience of rim protectors (on a 2004 SEAT Leon Cupra R aka Spanish version of VW Golf Gti MkV but better and with 225bhp) was that they work for one touch then they're gone, hence my interest in advice about 215s, 225s, 235s, 245s ..........

Don't care (much) about rotational mass.

Before someone raises it, also don't care about (much) about unsprung weight.

Would like more comfort.

Would like higher gearing.

Thoughts?

[Benny]

The lower the weight of the wheel and tyre, the more comfortable the car will ride as there is less mass to move up and down. Not the other way around.

I run 215/40/17's on the rear of my SP, on 7" wide rims, and they do protect the rim better than the 205's I've got on the front.
You might think you want to gear it up, but you will notice a decrease in acceleration and you won't find much of a fuel saving however.

Regardless of which tyre you choose, check out the rolling diameters if you are going up to a 215 tyre, as with some brands this will mean a greater diameter, and on other brands it will be the same (more or less) as their 205's.
Going to a 225 will definitely increase the rolling diameter over a 205 or 215 tyre.

[davekmoore]

The lower the weight of the wheel and tyre, the more comfortable the car will ride as there is less mass to move up and down. Not the other way around.

Fair comment. I'm actually thinking a 45 profile will have more give in it. To be fair the car is never actually uncomfortable so staying with 40s is still an option, but wouldn't do the increase in gearing as effectively.

I run 215/40/17's on the rear of my SP, on 7" wide rims, and they do protect the rim better than the 205's I've got on the front.

By "better" do you mean completely or just a bit? Any clearance issues? Would you get away with 225s as well?

Anyone else able to confirm what sizes you can go to without clearance issues?

You might think you want to gear it up, but you will notice a decrease in acceleration and you won't find much of a fuel saving however.

Bit more relaxed criuising though, and more useable first and second gears although the change in gearing is likely to be marginal (see below).

Regardless of which tyre you choose, check out the rolling diameters if you are going up to a 215 tyre, as with some brands this will mean a greater diameter, and on other brands it will be the same (more or less) as their 205's.
Going to a 225 will definitely increase the rolling diameter over a 205 or 215 tyre.

Staying with 40s, 215s should generally increase gearing by 1.3%, 225s by 2.7%, 235s by 4%, 245s by 5.4%.
Going to 45s, 215s increase gearing by 5%, 225s by 6.5%, 235s by 8% and 245s by 9.5%

Good point on checking the rolling diameters. Thanks for that and for the rest of your thoughts.

[sliq]

you've probably all seen this, but:

http://www.miata.net/garage/tirecalc.html

[davekmoore]

you've probably all seen this, but:

http://www.miata.net/garage/tirecalc.html

Thanks sliq, that is indeed where the %age gearing increase info came from.

Anyone got any info on running/higher profile wider tyres on 17s?

[Luke]

The only 2 options I would personally go with other than the 205/40/17 stock size are.

205/45/17 - More common size, so can jag specials on tyres.

or

215/40/17


Seriously though if you want to make it more "comforable" go and buy a set of 16's and put 225/45 16's or buy a 1997 el falcon!