inslowoutfast

iTrader: (8)

Looking to get larger race rubber for next years track season. Going to upsize from 255 to 275 on a 17 inch wheel. Could people who have actual experience with both sizes for road course use not drag or autoX...please chime in.

Was there a significant difference in grip. Was there a too much of a headache to fit them on the car. IE spacers, fender rolling, etc... Actual setup specs? Alignment, fender work, wheel size offset. Was there a loss of steering feel? Not worth the trouble?

I think this is invaluable information for those who track their cars and would appreciate if post are made with factual info as oppose to the all too often, I think my friend or I think some people.....so and so.

Thanks all.

Speed Element

iTrader: (270)

It depends on what width of your 17s and what type of 275s you are using. If you are running 17x9.5s, 275 sized tires will work fine and dandy.

we are currently running 275/35/18s on 18x9.5 wheels (+12 and +15) on our race car. rear fenders are shaved and fitted w/ Voltex over-fenders, and the fronts are HRS 20mm wide fenders.

alignment spec : -3.8 front and -2.8 rear

OHLINS Flag-L series
10kg springs front
12kg springs rear

Tires: Nitto 275/35/18 NT01s shaved

Jeff_Jeske

iTrader: (66)

^ Love that front bumper.

I heard that running wider than 255 will definately slow your car down in the straights. You need more power to match the added stick.

inslowoutfast

iTrader: (8)

Any excuse to increase horsepower is a good problem. Honestly my straight line speed is not a concern. It's my cornering speed I would like to improve. Speed element thanks. Any others with hard numbers and feedback?

WarmPepsi

iTrader: (35)

all depends on the tracks you're running.

275's obviously require fender modification.

I'm sticking with 255's this time around. Quicker on the tracks I run. Heck, a 235 might even be faster than what i have, but i'll stay with the 255's

letMeIn

iTrader: (12)

depends what offset of the wheel you going to get. 275x17 have tall side wall, you will have to modify front and rear fenders. Probably rear bumper bolt will have to be shaved. May even need spacers upfront to clear coilovers. All depends on the offset of the wheel, what Rcompund tire you are going to get, and if they are shaved or unshaved.

its possible tho, i have seen 1 guy on evo-ny has done it. there are probably more. what kind of suspension are you running? Wouldn't it be better to stick with 255s and do some coilovers,bushin,swaybar upgrade ??

I am running 255x40x17 on 17x9.5 rim +25 offset. I had to roll both front and rear fenders, as well as shave and relocate the rear bumper bolt. Im from NY as well. If you need someone to roll your fenders for cheap let me know. I can also help you relocate your rear bumper bolt.

Im running Robispec clubsport Kwv3. 450 front/500 rear. To fit 275 upfront I would have to get wider fenders for sure, rear I think I could get away with on a +25 offset rim

The front will be a ***** to make them fit. Heres me at Pocono North. Look at front suspension compression.

WarmPepsi

iTrader: (35)

Do what? 275's will fit under "pulled" fenders. a simple yank on the fronts (being aluminium) brings them clear. I know, i've been there.

Not sure why you're running such a large rim for that tire though. With a properly setup robi suspension, and the kw's, you don't need replacement fenders though.

And the rear has the issue of rubbing the trailing arm... you don't want that rubber any more inboard than it already is.

edit: and as far as the 275 having a "taller" sidewall, it's less than 1/8 of an inch difference (with the 275's being slightly taller.)

letMeIn

iTrader: (12)

I like the GTR face look and don't see too many people running 17x9.5 +25 RG2s.

As for fitting 275 infront, hmm on a +25 I don't think I would be able to fit them. First, without rolling front fenders, I rubbed 1/2 of the front lip on the very first autocross. Then I rolled them all the way in, which helped a lot. But if you notice the middle part of the fender is very thin and flexible. I pushed it as much as I felt it was safe and it always came back to the same position, except the 2 parts that the fender liner attaches to. I was able to push them out , and they stayed out, since they are thicker than the middle.

NT01 specs
.......size ............... Inflated Diameter..........Width........Revs/mile

255x40x17........................24.92............ .....10.35...........834

275x40x17........................25.55............ .....10.91............813

.63" taller and .56" wider.

in NT01 case they are little more than 1/8" taller . On a 38 offset you may be able to fit them, but the lower you go the more you have to modify your fenders. Just look at the picture below. Look how much +25 offset pushes the wheel/tire outside.

WarmPepsi

iTrader: (35)

not sure what an nt03 is, but i was quoting for ra-1's.

..sitting in my garage in both 255, and 275 (x40x17)

Matt2.8NJ

iTrader: (7)

Search my posts.

I have a full write up on how to run 275's - step by step fender rolling, offsets, wheels sizes, etc..

Posted early this year.

chrisw

iTrader: (2)

replied to your PM... but here is the response for everyone to read...

seems to be a bit of confusion here. Keep in mind, my application is for autox, but the fitment issues are the same if you are on the street, track, or autox setup...

anyway....

I run a buddy club p1 qf rim (17x9 +35mm offset) with a 3mm spacer for spoke/caliper clearance. It's a bad **** rim to run, very very light and exceptionally strong. I highly recommend them if you have the budget.

anyway. I run a kumo v710 275/40/17. According to tirerack.com, it has a sectional width of 11.4 inches. This is the key measurement you need to keep track of when sizing tires to fit. Not all 275's are created equal, and the v710 is the widest that I know of.

for example:

hoosier R6 11" sectional width
kumo vicoracers 11.1"
Michelin pilot sports 11"
Toyo RA1 10.9"

all tires are the same size, but different widths.

So given that I have a big fat tire to fit under the fenders, here are the main problem areas that I have

In the front, I have worn out the inner fender liners. At full steering lock, I rub on the inside of the inner fender well in front, and when I had bad spherical bearings in my camber plates, this let the tires just rub a bit on the rear of the front inner fender well against the passenger compartment. This may be an issue if you add a lot of caster from the camber plate, but that would be a silly amount of caster to run, but keep in mind this might be an issue that a 5lb sledge hammer can fix

Also at the extreme limits of body roll, I have polished my fender lips, but this has stopped now that I have better (uber stiff, barely streetable) spring rates.

In the rear, I have polished the rear trailing links. That's it. With the camber you are running in the rear, you won't have much fender well rubbing unless you have a nasty tank slapper over a harsh bump. You might rub a bit on the bolt that holds the rear bumper cover (it's just at the right place where you can't easily roll the fenders ) but that more an annoyance at it's worst.

I rolled the rear fenders anyway just so I could drive on the street with the V710s, I would recommend it for a track car as well.


Fitting a 275 is fairly easy. I would easily consider running the toyo's on the street as a summer tire, you have the clearance with 17x9 rims in the +32 - +35 offset range.


Oh yeah, forgot to add to the PM, you need to maintain a proper ride height as well. Not only for maintaining the correct roll centers and such, but also for correct tire clearance.

I have the vishnu ohlins and their recommended ride height is measured from the wheel center to fender lip.

I have 13.6" in front, 13.5" in rear according to their setup documents. You definately do not want to slam the suspension with such a wide tire (for those street image folks)

letMeIn

iTrader: (12)

ok Toyo RA1s.

275x40x17 width 10.9" diameter 25.7"
255x40x17 width 10.4" diameter 25"

unless you shave them, don't see how you can get 1/8 of an inch difference between 255 and 275. I was talking about NT01s in my post srry, my bad

Speed Element

iTrader: (270)

I had to modify my Voltex kit (a lot of trimming and cutting on the front bumper, side skirts and rear bumper) in order to fit 275/35/18s they sit much wider and taller than my street setup..

555R

iTrader: (5)

im in NJ and have a fender rolling tool
Im debating on doing the rental thing with it or selling it...
i dont have a heat gun though
i bought it and my friend used it to roll two cars fenders and I havent used it yet as my current setup didnt require any mods at all
17x9.5 RPF1s 38mm with a 20mm spacer up front
and 255/40s
fits like a glove

WarmPepsi

iTrader: (35)

dude, don't believe all the numbers you read as factory specs. Until you physically measure the tire, you don't have a value.

Measurement was from the edge of the lip of the wheel, to the solid line around the tire (outside of the markings).

Regardless, 275's aren't bad, run what you want, just setup your car for what you plan on running. A car running 275 nt01's is going to be setup differently than a car running 255 ra1's.