Adverse effects of upping tyre size on standard wheel

[Fantuzzi]

I've recently had a really unenjoyable time trying to find tyres that 1/ fit my car, 2/weren't terrible and 3/that were available to purchase this side of Christmas.

I found a set which were a good price, but it took a lot of faffing around to get something half decent in my size.

But I feel I may have neglected something that would have made my life both easier, and my car handle better! Upping the size of my tiny 185/55/15 fronts.

The car in question is a mk3 mr2, on pre facelift 15 inch wheels, the standard tyre size is 185/55/15 fronts and 205/50/15 at the rear. I would often find that sporty tyres would be available in the larger rear size but not the smaller fronts. Grrr.

I know the MR2 Racers run R888 on 195/50/15s on the standard front wheel, and I've heard it suggested in other places as well. But would there be any adverse effects to this? Immediately I can think of benefits, but is there any downsides to this?

Any help would be great, as having something sporty on the MR2 was the plan, but it seems the options I had lined up decided to change size ranges or discontinue!

[TheRealFingers99]

The bigger tyre may be OK -- you need to see what rim size (J or JJ size) the manufacturer's recommend.

But I can't see the point -- unless you're doing trackdays or have fitted a proper engine, the Uniroyal Rainmaster 3 should be just fine. £47 and a few pence from Camskills.

[HertsBiker]

I'd stick with the narrower tyres on the front. I once fitted wider on the front of a Smart and it became an over steering horror. 30 miles were enough to make me go back to the garage and revert to standard.

[f1nn]

I actually think that would be okay...if memory serves me correctly that is a common size upgrade for 205gti 1.9s.

The only thing I would add is what's the reasons for wanting to do it? I personally think increasing grip on a road car over what it came out of the factory with is rarely an improvement.

I remember driving 106 Rallye on the standard wheels and tyres and it was great, adjustable and poised. It then had some yokahama trackday types rubber fitted and it just felt over tyres and dead......ruined the car IMO.

More grip=not always better

[Herman Toothrot]

On my MR2 Roadster like many who have a bit more power than standard run 195/50/15 front and 225/45/16 rear, so stagger remains. However with normal power levels I'd happily reduce the size of the rears, as you said the race series uses 15" all round as per pre facelift and 195 R888's again all round I believe.

[TooMany2cvs]

Fantuzzi said:

I've recently had a really unenjoyable time trying to find tyres that 1/ fit my car, 2/weren't terrible and 3/that were available to purchase this side of Christmas.

I found a set which were a good price, but it took a lot of faffing around to get something half decent in my size.
185/55/15

http://www.camskill.co.uk/m53b0s287p0
Oh, look, a good choice of decent tyres at reasonable prices available quickly.

[PedroB]

185/55 R15 is the standard size on my MGF at the front, with 205/55 R15 on the back.

A lot of guys swap to 195/50 R15 on the front as the tyre choice is wider and generally a little cheaper. Toyo Proxes in that size seem to be well regarded and I'm fitting a pair to the F on Saturday.

[John145]

I managed 195/50 R15 on the front with 225/50 R15 on the rear of my MR2 and didn't die.

https://www.youtube.com/watch?v=t2bhsQTJF2M

[Rick Cutler]

Take the Caterham 160 for example, Narrow steelies. These were fitted to make the car more fun, if it gripped better then it would it be a slow boring boat.

[vrooom]

I run 205/50/15 all around on my mr2 roadster as fitted by previous owner, It doesn't oversteer at all, it made more netural, you will be fine.

[Fantuzzi]

Just to say, the idea of upping the sizes isn't for more grip, rather its so I have a wider choice of sporty tires, mainly the Yoko ADO8r, and a range semi slick tires. The rears are a odd size, so have little choice there as well, but most of the tyres I was after were in the size, so it was just the fronts that were the issue. Hence the change.

TooMany2cvs said:

Fantuzzi said:

I've recently had a really unenjoyable time trying to find tyres that 1/ fit my car, 2/weren't terrible and 3/that were available to purchase this side of Christmas.

I found a set which were a good price, but it took a lot of faffing around to get something half decent in my size.
185/55/15

http://www.camskill.co.uk/m53b0s287p0
Oh, look, a good choice of decent tyres at reasonable prices available quickly.

Well done.

Now go back, look for the tyres that you could also get in the rear sizes. Go on. What's that? Only 9 tyres that aren't budget brands? Oh dear. Go and see how well those tires have been received in both tests and owners opinions. Goodness they aren't really anything special are they? Oh well those Pirellis look nice. Uh oh! Not in the front size! Toyos, they fit! Oops! Very soft sidewall according to owners, not so good! Uniroyals? Same thing, and 1 month ago when this was all happening, they didn't have the sizes in! Oh dear, looks like my hopes to get a sporty tyre for a sporty car isn't going well!

Shame because, if the front sizes were bigger I could get Yokohama ADO8Rs, a048, toyo r888, which is what I was after...

Not so easy is it 2cv?

[craig_m67]

WTF .. You ask for help and then sarcastically dismiss others trying to help, you sir are a clown.

[TheRealFingers99]

The lack of decent rubber in 15s isn't exactly new or news. Blame it on the fashionistas who believe 18" is the way to go.

Equally the idea that soft sidewalls are automatically bad for handling is a myth. I once tested same size Falkens (pretty stiff sidewalls) against Rainsports (albeit an earlier set than the 3) back to back. Result -- the car handled better and more predictably on the Rainsports, but the Falkens were (surprisingly) nearly as grippy. Different cars will get/give different results, natch.

[BritishRacinGrin]

I'd suggest that you'd notice greater differences in grip between a range of tyres of the same size compared to two tyres of the same size where one is 185/55 and one is 195/50. All of those who are saying that the extra 10mm is going to upset the balance are probably overestimating the difference quite a bit.

5.4% more width doth not make 5.4% more grip. with pressures being equal, the tyre contact patch will be practically the same, which means that your force per unit area is practically the same.

Adverse effects will be very limited as it is such a small change, but theoretically speaking;
-Wheel/tyre interraction. Depending on your rim width, you may have more or less side to side movement of the tread compared with the wheel
-Aquaplaning. Like-for-like, wider tyres are more likely to aquaplane, in theory at least.
-Tramlining. Like-for-like, wider tyres are more likely to tramline, in theory at least.
-Approximately 6mm less front ground clearance!?

Basically, go for it. It's a well-trodden path for VX220 owners too, for the same reason.

Edited by BritishRacinGrin on Saturday 2nd August 05:28

[TooMany2cvs]

Fantuzzi said:

Well done.

Now go back, look for the tyres that you could also get in the rear sizes.

You specifically asked about the fronts, and said there was no choice in the fronts. There is.

Given that the sizes are staggered, I don't see the problem in mixing decent quality brands - or models within a brand - end to end. You may differ. Fair enough, but my lack of psychic abilities didn't allow me to divine that, nor did it allow me to divine your particular experiences and preferences. If specific MR2 experiences were your goal, perhaps an MR2 forum would have been a better place to ask?

Forgive me. I shall attempt to read between the lines of your posts better in future.

Edited by TooMany2cvs on Saturday 2nd August 09:11

[BritishRacinGrin]

Fantuzzi said:

the standard tyre size is 185/55/15 fronts and 205/50/15 at the rear. I would often find that sporty tyres would be available in the larger rear size but not the smaller fronts. Grrr.

TooMany2CVs, it's right there in the opening post.

[TooMany2cvs]

BritishRacinGrin said:

Fantuzzi said:

the standard tyre size is 185/55/15 fronts and 205/50/15 at the rear. I would often find that sporty tyres would be available in the larger rear size but not the smaller fronts. Grrr.

TooMany2CVs, it's right there in the opening post.

I read that as "There's a pretty much non-existent range of sporty tyres available in the front size", rather than "Particular tyre models don't tend to be available in both front and rear sizes to keep it all matching".

It is one of the big problems of running older performance machinery - my old c900T16 was starting to scrape the barrel in terms of what could be got.

[Qwert1e]

On any mid-engine car I'd be cautious about fiddling with tyre specifications. It's very easy to put the car out of balance. I'd be wanting reassurance from a reliable club or other source before and expensive, and potentially over-exciting, experiment.

[Fantuzzi]

craig_m67 said:

WTF .. You ask for help and then sarcastically dismiss others trying to help, you sir are a clown.

It wasn't help though was it? It was a pissy 'you haven't looked properly post'.

It was clear what I was after, performance tyres. I stated that the rears have sporty options, the front don't. So giving me a link to 30+ crappy front tires on camskill wasn't what I was after. I wanted advice on upping the tyre size from 185/55 to 195/50 to allow me to have some choice on some proper performance tyres.

TooMany2cvs said:

I read that as "There's a pretty much non-existent range of sporty tyres available in the front size", rather than "Particular tyre models don't tend to be available in both front and rear sizes to keep it all matching".

But sporty tyres are pretty much non-existent in the front size. That's the point and my problem. The Unyroyals have soft sidewalls, as do the toyos. Which I really didn't want, as a lot of owners found them floaty and big dissapointment. The plethora of other tyres in 185/55 on camskills aren't very good either, none of them got very good owner or test reviews - I checked to see if there was anything worth having, so it was a pain in the ass to get something that would enhance the cars feel rather than compromise it.

[craig_m67]

I see the shoes (rears at least) fit...

Edited by craig_m67 on Sunday 3rd August 01:50