cnMax Posted June 10, 2007 Share Posted June 10, 2007 Yes, the recommended minimum width to mount most brands, i.e. RA-1s, is 8.5 in. BUT in quest of lighter weight, are using 8 in. wheels still acceptable, safety wise, as there are more options for my fitment? Anyone out there using RPF-1s, SSRs, or ?? Quote Link to comment Share on other sites More sharing options...
Ultimate Altima Posted June 11, 2007 Share Posted June 11, 2007 I'd be willing to put 255's on 8 inch rims, but no more. Motegi traklite's and traklite 2.0's are alos very good rims. Quote Link to comment Share on other sites More sharing options...
1LapSRT Posted June 12, 2007 Share Posted June 12, 2007 From someone who actually owns a car: That is too short of a sidewall to put a 255 on an 8" rim. If you go to a 45 series, it would be do-able (barely). Quote Link to comment Share on other sites More sharing options...
kbrew8991 Posted June 12, 2007 Share Posted June 12, 2007 people put street tires that size on the stock Mustang wheels alot can it be done: yes will you loose contact patch: probably a little which wheel is more optimal for your setup: don't know Quote Link to comment Share on other sites More sharing options...
sb Posted June 12, 2007 Share Posted June 12, 2007 This question can't really be answered here, at least not without more information. There are many factors that determine if you'll be able to effectively gain a larger contact patch, e.g. tire make/construction, suspension setup, etc. The bigger issue is fitment (and potential rubbing issues), which can vary by springs/coilovers etc. Having said that, I've fitted a 255x40x17 RA1 on an 8 rim. Unloaded width will be approximately 245 due to distortion, but it fits fine. It's a common fitment for STIs and Evos. I didn't like the results. Overall it was slower for me compared to a 235x40x17, almost entirely due to the fact that my camber was maxed on my stock setup to -1.25. What I did gain was a noticeably heavier tire that increased unsprung weight and decreased acceleration. I was very aware of the extra mass. Braking was slightly improved, but entirely offset by slightly slower speeds on exit. In my specific case, I believe more camber would make a 255 worthwhile, but at the moment I'm only using about 4" of tire in the corners--wider won't change that. Quote Link to comment Share on other sites More sharing options...
Ultimate Altima Posted June 13, 2007 Share Posted June 13, 2007 "From Someone who actually owns a car"? What's that supposed to mean? I may be a kid, but I know what I'm doing and what I'm talking about. I would like a little credit, thank you very much. Quote Link to comment Share on other sites More sharing options...
Fair Posted December 13, 2007 Share Posted December 13, 2007 A 255 on an 8" rim is not ideal at all, no. Its a bad squeeze. A 255 would be better suited to a 9" or 9.5" wide wheel. Gets more of the available tread on the ground to do some actual work, and reduce carcass movement/deformation. I raced for 3 years on 255s in the same car... and used 8.5, 9" and 9.5" wide wheels with the same width tire. The best tire wear and grip test data came with the 9.5" wheels, but they were $2200/set 3-piece custom wheels and somewhat heavy. We settled on 4 pound lighter 17x9 cast wheels that were half the cost, and it worked pretty well overall. Well, until we moved up to a 18x10 wheel and a 265... 255/40/17 on 17x9.5" wheel Look at the recommended wheel widths the tire manufacturers publish for every tire size, and go towards the wider end of the range they publish if possible. Sure, sometimes you give up a 1/2" of wheel width to get into a much less costly set of non-custom wheels (going to 3-piece customs can drive pricing up 100% or more), because sometimes budget matters. Quote Link to comment Share on other sites More sharing options...
kbrew8991 Posted December 13, 2007 Share Posted December 13, 2007 it also really depends on which particular tire brand/model, as some are on the narrow side comapred to tires of the same "width" and some are on the wider side... Quote Link to comment Share on other sites More sharing options...
loudes13 Posted December 14, 2007 Share Posted December 14, 2007 it will fit Quote Link to comment Share on other sites More sharing options...
Fair Posted December 14, 2007 Share Posted December 14, 2007 it also really depends on which particular tire brand/model, as some are on the narrow side compared to tires of the same "width" and some are on the wider side... it will fit I agree, "it will fit", and hold air, but a 255 on an 8" wheel is just anything but a "good" fit. The car manufacturers tend to go on the skinny side when it comes to fitting wheels, which allows the tires to have enough "bulge" to keep the rim edges from being scraped up when drivers brush up against curbs when parking. One of the very first 255 fitments was the 255/40/17 on the C4 Corvette Z51 (1988 I believe), which was on a 17x9.5" wheel. There's plenty of examples of 255s on 9" wheels on OEM set-ups. Let's look at some real tech, too. Doing a quick check of tire manufacturer recommendations for the 255/40/17 size in "competition" or "extreme summer performance" tires on Tire Rack shows us this: Tire Model = Recommended Wheel Width Range / Measured Section Width (and Tread Width if given)==================================================================== BFGoodrich g-Force R1 = 8.5-10" / 10.2" Kumho VictoRacer V700 = 8.5-10" / 10.6" (Tread Width is 9.7") Michelin Pilot Sport Cup = 8.5-10" / 10.7" Yokohama ADVAN A048 = 8.5-10" / 10.3" (Tread Width is 10") Bridgestone Potenza RE-01R = 8.5-10" / 10.3" (Tread Width is 9.4") Dunlop Direzza Sport Z1 = 8.5-10" / 10.4" Yokohama ADVAN Neova AD07 = 8.5-10" / 10.3" (Tread Width is 9.9") AZENIS RT-615 = 8.5-10.0 / 10.3 (Tread Width is 9.4") When the tire manufacturer had a measured tread width I included that also (which shows some notable variances). Now I didn't cherry pick those models, that's everything in a Competition or Extreme Performance Summer tire that Tire Rack sells (minus "colored smoke" nonsense) + the Falken RT615 (Hankook and Hoosier don't make this size) in this size 255mm tire. Notice how all of the manufacturers put 8.5" rim width at the lowest range of the recommended wheels. And how 10" was the max. Wouldn't it seem that a 9 to 9.5" would be in that recommended range, and an 8" would not? Again, I've personally run this size in many of those very tire models, in competition use (AD07, RE-01R, V700) for over three years (avg 25 events + dedicated test sessions per year) and on wheels of 3 different widths. And tested each on a 200' skidpad, timed course, pyrometer, data logging... and the wider wheel for this size tends to works better (9.5"). We didn't have a 10" wheel width, which I would have liked to have used for testing (we moved to the 18x10" instead and a 265 tire), but among the 8.5", 9" and 9.5" widths we tested, the results got better as we moved to the ever wider wheel. The one spoiler was that the 9.5" wheel we used in testing was considerably heavier (3-piece custom, the only option) and the 9" showed similar lap time results, probably due to being 4 pounds lighter and having less inertial mass for braking, acceleration, etc - which is hard to quantify on a skid pad or pyrometer, other than with lap times. Its not the best test ever done, for sure, but the pyrometer data and measured tire wear over the life of the tire did tend to prove the benefits of the wider wheel in our use. For a street car, sure, squeeze a ~10.5" section width 255mm tire onto an 8" wide wheel if you want, but if you are running that way in competition you are "wasting tire" with a wheel width outside of the recommended range, and giving up time. Do some testing - prove it to yourself. *Disclaimer - I don't claim to be a tire engineer, but I did sleep at a Holiday Inn Express last night. Cheers, Quote Link to comment Share on other sites More sharing options...
kbrew8991 Posted December 14, 2007 Share Posted December 14, 2007 and the beating a dead horse award goes to... Quote Link to comment Share on other sites More sharing options...
Fair Posted December 17, 2007 Share Posted December 17, 2007 and the beating a dead horse award goes to... Hmm... point taken. After reading several more threads here I can see that there's not much tech discussion going on... just rules and event banter. I'll make that my last post about anything technical. Thanks, Quote Link to comment Share on other sites More sharing options...
fast_frank_d Posted December 17, 2007 Share Posted December 17, 2007 Hmm... point taken. After reading several more threads here I can see that there's not much tech discussion going on... just rules and event banter. I'll make that my last post about anything technical. Thanks, Fair, I (for one) was happy to see your detailed research and technical reasoning. I wish more people were this thorough when backing their position. Most people who ask questions here are just as interested in the “why†Quote Link to comment Share on other sites More sharing options...
kbrew8991 Posted December 17, 2007 Share Posted December 17, 2007 eh, it was a more of an "this is a really old thread" than anything else.... you'll find some people needing technical advice, I wouldn't give up on it yet Quote Link to comment Share on other sites More sharing options...
gotspoonJDM Posted December 21, 2007 Share Posted December 21, 2007 i run BFG r1`s on 8 inch wheel Quote Link to comment Share on other sites More sharing options...
1LapSRT Posted December 27, 2007 Share Posted December 27, 2007 i run BFG r1`s on 8 inch wheel I guess 255's work different on Japanese cars, huh? Quote Link to comment Share on other sites More sharing options...
Neon2dmaX Posted December 27, 2007 Share Posted December 27, 2007 FWIW... why not use the Hankook Z214. It comes in a 245-40-17 which is intended to fit on an 8" rim, and after factoring in the cost of shaving, is actually lass expensive than the Toyo RA-1. Frisby Tire shows the new Toyo R888 in the same size, but that is probably a misprint, and nevertheless, is quite a a bit more expensive than the Z214. See: http://www.hankooktireusa.com/product/tire_race_detail.asp?pid=751 and http://www.frisbyracetire.com/hankookracetires.html A few years back, I had a set of 215-40-16 tires installed on a 6" wide rim, a full one inch less than the minimum recommended width. The installer told me to look for cracks on the sidewall since the narrow rim would cause more flex in the sidewall on a continuous basis. After some time, sure enough, the sidewall started to split. So, it can be done, but I can't say that it could be recommended. Quote Link to comment Share on other sites More sharing options...
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