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I'm in the process of ordering a set of wheels - thinking staggered 15x8, 15x9, 205/50 and 225/45 or 50
Recommended wheel widths for thos sizes would probably be 7" and 7.5"
I hear conflicting opinions on whether a slight stretch is a good idea or not. I read a lot of internet opinions that the slightly stretched tyre is if not out-right faster, is at least easier to drive at the limit and therefore faster. Is this true or false? Opinions?
Stretching tires is an abuse of the tires design. It will not make it perform better, in fact it will probably increase wear due to the side wall angle.
I run 15x7 with 205/50 which are not a stretch at all. Very good grip.
But let me put this out there. Racing classes dictate maximum width of wheel as well as maximum width of tire and then when wheel widths are limited they redesign tires to work on narrow wheels.
Because the wider wheel has been shown to be faster again and again in racing.
Many factors though on whether it will be faster for you.
Suspension and set-up. Driver experience. Amount of stretch.
My opinion is 205mm wide tire works nice on 7.5-8.5mm wide wheel, 225 works nice on 8-9" wide wheel.
What tires are you looking to run? Different tires come in wildly different widths. For instance in 15" diameter Toyo R888 run pretty wide.
This 240 has 235/50-15 R888 on 15x9 front wheels and 15x10 wheels in the rear to illustrate the difference in sidewall profile.
^ great photo!
its not going to be for any racing class, just weekend warrior duties and occasional casual track days. Its a 400+ rwhp fb so grip is hard to come by and longevity isnt really an issue.
suspension is 275/150 spring rates and illuminas. -2 deg camber 6 castor. May be upgrading to better coilovers with similar spring rates later in the year.
so far the tyres im looking at are Nankang ar-1 , toyo r888r, possibly kumho v70a if ican capitalise on factory clearance. Maybe hankook rs4.
Going off that pic the toyos run pretty wide. I'm going for something inbetween the front and back wheels on that. So that setup would be pretty reliable? No issues with tyres un-beading or perishing?
Ive worked out my widths and offsets off the current wheel and tyre set up, 15x7.5, 225/45r15 hankook rs3 all round. In order to fit a wider wheel at the front i will need less offset to clear the strut and thus a narrower tyre. Which i think will aid handling and tracking anyway with the pathetic fb manual steering box and generous castor.
Ive got plenty of room though, depending on the width of whichever brand tyre i end up with i can roll the guards if i have to.
You’ll be fine. That’s hardly stretch. I’ve run 205’s on 8’s for years. There is a popular Miata website that tested wheel and tire widths on lap times, it got to the point where a 225 worked best on a 10” wheel. Do it, and enjoy the increased grip.
the tyres im looking at are Nankang ar-1 , toyo r888r, possibly kumho v70a if ican capitalise on factory clearance. Maybe hankook rs4.
In my 400rwhp/400rwtq FC I was impressed by Maxxis RC-1 traction for accelerating and streetability despite being a slick. I think part of it is the tire compound comes in 20F sooner (140F compared to 160F) than the NT01/R888 compound and I think some of it has to be construction as well. It comes in 205/50-15, 225/35-15 and 245/40-15.
Other DOT-Rs I have experience with
Toyo RA1
Nitto NT01
Toyo R888
Hankook TDs
BFG R1S
Kumho V710
When you have a stretched tire you don't have as much of the "warning signs" of tire noise and sidewall flex before the tires transition into slip angle.
When they are stretched you have more of a seamless transition into gripping to slip angle- so if you are comfortable driving deep into slip angle it is a smoother more predictable drive. Same could be said of just sidewall construction/stiffness in general. If you like NT01 you might not like stretch, if you like R888 you will probably like stretch.
^ I'm in Australia. The maxxis sounds amazing but I have not seen it here and slicks are a no go. Half the battle is having tyres that dont look silly as far a keeping the pwers that be happy.I like the idea of the nankang - excellent pricing and supposedly excellent cold peformance, but might attract attention from Mr PoPo at the next random breath test for looking "slick-like"
The Kumho v70a fascinates me, I dont know much about it but i believe its a full fledged competition tyre but the tread pattern, although very shallow, looks good for funnelling a bit of rain and looking like a normal tyre. I mi9ght be able to get some at 100aud each that have probably been shelved to long - about half the price of other cheap r-spec's and about a 3rd or 1/4 of the normal price. https://www.kumho.com.au/tyres/racing/ecsta-v70a/ The toyo ra1 intrigues me. How did you find those?
Aloso thoughts on the Kumho v710?* another tyre that has crossed my radar and comes in the sizes i want. How doed it compare to, say a hankook rs3 or a dunlop star spec?
* edit. Sorry i was thinking v720
The Kumho v70a fascinates me, I dont know much about it but i believe its a full fledged competition tyre but the tread pattern, although very shallow, looks good for funnelling a bit of rain and looking like a normal tyre
We used to use the V70A (called V700 here in USA) back in 2006ish on Miata's, CRXs, and Vipers in my local car club. They are alright. Work well cold, very fragile- didn't work out on the Vipers. Much better for light cars. A lot like the Avon DOT-Rs for the Lotus(es)(i) (IDK the plural of Lotus).
They are maybe a tad slower than the best 200utqg street tires available today like the Bridgestone RE71R. I would say they are on par with Toyo RA1, but more biased toward cold performance.
In Hot Version Touge Challenge on Gunma Cycle Center they allow competitors to use the V70A even though the rules are street tire only- hard to say if they have an edge over the AD08R or RE71R.
---------------
The V720 is a second rate 200utqg street tire- not quite as good as RE71R or even AD08R, but better than third rate 200utqq tires like RT616K or 595RS-RR. My friend raced on V720 last year and is on 595RS-RR this year (which aren't quite as fast as the old 595RS-R BTW- as tested).
This car has 205/50x15 Hoosier SM7s on the front and 225/45x15 Hoosier R7s on the rear. The wheels are 15x8s that have a 35mm offset and to get them to fit under the stock fenders I run a 5mm spacer on the rear and 35mm adapter/spacer on the front. Hoosiers physically measure wider than any of the tires you are looking at running.
From my experience there is a tangible lap time difference between a 205 on a 7" rim and one that is mounted on an 8" rim.
Thanks guys. Great info. Kinda surprised the v70a is just a 2nd rate 200tw tire. For some reason I thought it was something a little bit more savage. Not surprised about the v720 though.
Are you sure its the same thing though? I was just looking at an online retailer, they come in four different compounds ranging from "hard" to "super soft",, that doesnt sound like a 200tw style "hybrid" tyre to me...
In my experience, a slightly stretched tire will make a car corner significantly better. This is because as weight transfers to one side of the car, the tire's sidewall tends to "roll" or move to the outside of the wheel. By having a slightly stretched tire, you will "roll" on the tires tread instead of the sidewall, thus increasing overall grip. It is important to stress MODERATION. Slight stretch=Good, Stance stretch=bad.
Its not a 200 tread wear street tire, its an old school DOT-R that performs as well as todays top 200 treadwear street tires.
This tire-
I used to race on those tires - shaved to 4/32. None of the current 200 tread wear street tires are as fast as those tires. The V710 was faster but not allot faster.
Good info guys. Well I finalised the order on the wheels, they'll take about two months. Good to know there are plenty of tyre options. Will be keeping my eyes peeled for a good deal. Unfortunately they never got back to me on the $99 (aud) per corner clearance on v70a and the offer has been taken down off their website. Will keep looking around though. I get excited over new tyres, lol.
about 3 years ago we switched from a class that had a spec trie/wheel combo, 225/50/15 Ra1 or R888 on a 15x7 wheel, to a class that was points based. since we were kind of limited we ran a 205/50/15 and tried different wheels.
we tried 205 on an 8" wheel, and then on 9" wheels. the 205/50/15 on a 15x9 is about as fast as a 225/50/15 on a 15x7.
cliff notes, the tire manufacturer gives a rim width range for a tire, and for a race car you want the wider wheel.
Mazda actually since 1986 has fallen in line with this too. they always run a 205 on a 7" wheel, 225 on an 8" wheel, etc. and remember Mazda's test course is a race track.
^ This is good to know!
So i ordered 15x8 and 15x9 and will go a 225 on the rear either a 195 or 205 on the front depending which type of tyre i get.
Good to know this sizing works well and is not just "****-factor" so to speak lol,,,, well, it is a little bit (a lot). Hence the name lol.
Thanks. Yeah they are pretty nice. Im excited. Was a decision between those and these which I think look awesome as well, but the 03 just kinda looks more structural somehow, although i am sure they are both engineered to the nth>
^ This is good to know!
So i ordered 15x8 and 15x9 and will go a 225 on the rear either a 195 or 205 on the front depending which type of tyre i get.
Good to know this sizing works well and is not just "****-factor" so to speak lol,,,, well, it is a little bit (a lot). Hence the name lol.
that will be perfect! if you get the offset right, i think the front will fit under the stock fenders, 225 in the rear is possible too, but 15x9 will be tight everywhere.
^ there is a fair bit of room under the rear. If 245/40r15 were readily available here in Australia I would probably ordered 15x10 for the rear with more positive offset. Currently have 225/45 all around with no rubbing whatsoever on 7.5" wheels, however to go a wider wheel at the front introduces clearance issues at the strut, which means less offset which means a narrower tyre to clear the guard. Did invest in an ebay guard roller just in case.
03-26-18, 02:29 PM
