305 on stock SL rims

  • Forgive me if there is a thread somewhere that already address's this question. I did a search but could not find the information
    @rabtech If this is a duplicate thread please feel free to delete this one


    On Face book there is a post dealing with running a 305 tire on the stock SL rim here


    A little background regarding stock SL sizing


    Front: 225/45/18 Rims: 18X7.5 Diameter: 26.0"
    Rear: 255/35/20 Rims: 20x9.0 Diameter: 27.0"


    The recommended 305 size on an SL rim is a Nitto G2 305/35/20, which I do not understand it has a diameter of 28.43, which is 1.43" larger then the stock tire.


    The Nitto G2 305/30/20 has a diameter of 27.24 which is very close to the diameter of the stock SL tire.


    Why is it recommended to run the larger diameter 35 size vs the 30??? is it because the tire should be mounted to a 10" minimum rim width vs the stock 9.5" wide rim?
    The difference in percentage from stock to the 35 is 5.2% larger, which I think would throw codes.


    The 30 is within 0.7% of the stock SL rear tire


    Now if we compare the % ratio for stock SL front to rear we have 3.8%
    But it we use the 305/35/20 the ratio of stock front to this tire is +9.2%
    the 305/30/20 difference from front stock to this tire is 4.6%


    If anybody has information regarding running the 305 on stock SL rear. Please provide your experience and wisdom


    Thanks,

    John
    2017 SL LE Midnight Cherry
    :COILOVERSS::TURBOSS::MOTOROILSS::FILTERSS::COLDAIRSS::DONKEYSS:

    Edited once, last by Casey_SS ().

  • See this thread - REAR TIRE, my post # 15. While I haven't' found a specific formula describing the relationship between tire profile width and wheel width, based on the Budnik chart I copied the info from, as tire sidewall height increases the minimum required wheel width decreases. When matching wheel width to tire profile, always try to stay within the tire manufacturer's recommended sizes for safety and warranty reasons. Using a wider tire on a narrower than recommended wheel width increases the possibility of breaking the tire-to-rim seal with negative consequences and would probably void any manufacturer responsibility or warranty.
    As I posted in a different thread, I have read about folks running 305 tires on 9.5" rims (Mustang forums, IIRC), but that is generally a smaller wheel width than most tire manufacturer's would recommend and probably wouldn't be recommended by the tire manufacturers.

  • See this thread - REAR TIRE, my post # 15. While I haven't' found a specific formula describing the relationship between tire profile width and wheel width, based on the Budnik chart I copied the info from, as tire sidewall height increases the minimum required wheel width decreases. When matching wheel width to tire profile, always try to stay within the tire manufacturer's recommended sizes for safety and warranty reasons. Using a wider tire on a narrower than recommended wheel width increases the possibility of breaking the tire-to-rim seal with negative consequences and would probably void any manufacturer responsibility or warranty.
    As I posted in a different thread, I have read about folks running 305 tires on 9.5" rims (Mustang forums, IIRC), but that is generally a smaller wheel width than most tire manufacturer's would recommend and probably wouldn't be recommended by the tire manufacturers.

    @BKL thanks for the information. I know the recommended width for the 305 is on a 10" rim, vs the stock SL rim being 9.5" But it seems some people are running the 305


    One of my questions above which has not been make clear is the height of the tire a 30 vs 35. The 30 is almost the same diameter as the stock 255/35/20

    John
    2017 SL LE Midnight Cherry
    :COILOVERSS::TURBOSS::MOTOROILSS::FILTERSS::COLDAIRSS::DONKEYSS:

  • Actually, the stock SL rear rim is 20 x 9." See - Specs: 2018 Slingshot SL - Sunset Red | Polaris Slingshot.


    Here's the Nitto specs for the 255/35R20 and 305/35R20 and 305/30R20 tires -

    255/35ZR20 97W XL 211010 11.0 27.01 10.24 8.5-(9.0)-10.0 1609 @ 50 29.16
    255/45ZR20 105W XL 211140 10.2 29.06 10.04 8.0-(8.5)-9.5 2039 @ 50 31.97
    265/35ZR20 99W XL 211110 11.0 27.32 10.67 9.0-(9.5)-10.5 1709 @ 50 31.17
    275/30ZR20 97W XL 211310 11.0 26.54 10.94 9.0-(9.5)-10.0 1609 @ 50 30.74
    275/35ZR20 102W XL 211020 11.0 27.56 10.94 9.0-(9.5)-11.0 1874 @ 50 32.01
    275/40ZR20 106W XL 211100 11.0 28.66 10.94 9.0-(9.5)-11.0 2094 @ 50 33.36
    285/30ZR20 99W XL 211210 11.0 26.77 11.42 9.5-(10.0)-10.5 1709 @ 50 32.30
    285/35ZR20 104W XL 211440 10.2 27.87 11.42 9.5-(10.0)-11.0 1984 @ 50 33.07
    295/35ZR20 105W XL 211290 11.0 28.11 11.85 10.0-(10.5)-11.5 2039 @ 50 34.35
    295/40ZR20 110W XL 211270 11.0 29.29 11.85 10.0-(10.5)-11.5 2337 @ 50 35.94
    305/30ZR20 103W XL 211220 11.0 27.24 12.32 10.5-(11.0)-11.5 1929 @ 50 34.24
    305/35ZR20 107W XL 211420 10.2 28.43 12.32 10.0-(11.0)-12.0 2149 @ 50 35.27


    Increasing sidewall height allows use of a narrower wheel, so you might be able to fit a 295/45R20 (if anybody makes such a size) on a 9.5" wide rim, but a 9" wide rim will probably never be a good fit if you're trying to maintain a somewhat accurate speedometer reading using the Stock SL ECU tire settings. A wider wheel wouldn't affect your speedometer reading, but going to a much taller tire will definitely mess around with your speedo/odometer readings. I'm not sure if Polaris actually offers an SLR tire size for the ECU (I doubt it since the tire is only a little bit larger than the stock 255/35R20 tire). Just looking at Polaris' use of a 20 x 11" wheel with the 305/30R20 tire on the SLR would cause me to think trying to fit a 305 tire on a 9" wide wheel is too far outside any reasonable fitment. Some people may have done it, but that doesn't mean it's a smart thing to do. Most responsible tire shops wouldn't mount a tire that is significantly different from the manufacturer's fitment recommendations. Looking at the last line of Nitto's 555 info chart above tells me you should probably go with a 10" wide wheel, minimum. The least expensive wheel which I think might look ok with the existing front SL wheels would be this American Muscle 20x10 48mm offset wheel at $185 - Mustang AMR Charcoal Wheel - 20x10 (05-14 All) - Free Shipping. Generally speaking, you can usually trim about 2-3 mm from the Offset which would make this wheel a proper fit as a rear wheel or you could just leave it as is since it would only shift the center of the wheel a marginal amount to the right, but you might still find that it or all 3 wheels need repainting for a better match (or you may think it's just too different). I hope this helps some. Just remember this is my opinion and worth every penny paid for it! :D

    Edited once, last by BKL ().

  • Thanks @BKL for the information


    I'm wanting to go wider not sure if 11" or 12" wide


    I'm also looking at widening the stock SL rim that I have to 11 or 12 inch


    Rohana makes 2 rims that are similar to the stock rim
    RFX5 which is 20x11 and the FRX11 which is 20x12


    RFX5


    RFX11

    John
    2017 SL LE Midnight Cherry
    :COILOVERSS::TURBOSS::MOTOROILSS::FILTERSS::COLDAIRSS::DONKEYSS:

  • 1. I highly advise against putting anything larger than a 285/35/20 tire on a stock 9 inch wide wheel. It is too far out of recommendation and the tire is considerably bulged. They last thing anyone needs is the tire de-beeding under extreme use.


    2. Widening a stock wheel makes very little sense. The stock wheels aren't that nice to start with and it is expensive compared to other options. If you widened the wheel 2 inches to a 11 inch rear wheel, you would be inch too far towards your shock. This would mean that you need a big 1 inch spacer and new wheel studs or a spacer that converts to new lug studs.


    3. The best matches for a rear wheel are likely...

    4. If you want wide, just run what everyone else runs - 20x12 rim (one of the two above) and a Toyo T1R 345/25/20 tire


    5. I have a black Rohanna RFX5 with setup listed in #4 for sales if your interested - shipping probably isn't favorable though...

    Owner of Slingshot #263 that has some stock parts left on it. :D

    Edited once, last by TravAZ ().

  • I pretty much agree with what @TravAZ posted. Before I bought the American Muscle 10th Anniversary Cobra Style 17x10.5 28mm offset wheel, I had thought about widening a stock front wheel to 10.5", but decided against it for 2 reasons, primarily because that would have been a 50% widening which I felt was a little too much and because of the need for a spacer. In the end, the Am wheel does center to the left over 1", but that doesn't bother me since I've experienced no handling problems and the wheel only cost $150 compared to $around 400 for widening plus the cost of the spacer. Iwas able to add that wheel and a Nitto 555 G2 315/35R17 tire for around $400 all-in, which fit my budget constraints.

  • I researched this quite a bit a few months back and went with a 285/30/20. It's about the max that is recommended for a stock SL rim and doesn't change diameter too much (speedometer error). If you go wider, it will fit but the tire contact surface will egg out and be reduced as well as cause faster, center tire wear.

  • I must be the odd ball in the group since i really like the stock 2015 SL wheels. It's not a matter of cost since having the wheel shipped out, made 2 inches wider, shipped back, powder coated brings up the cost to almost double of what one new wheel would have been. But I'll tell you this; The look on people's faces (those who know slingshots and what the stock wheel looks like) is priceless when they see this big fat 345 tire on a stock appearing wheel. Even this past winter during Bike Week in Daytona, both Polaris people and a customizer of sports bikes were impressed to see that tire on a stock wheel. The small changes that yields huge results shouldn't be overlooked by the fact that there are other choices in wheels.




  • I must be the odd ball in the group since i really like the stock 2015 SL wheels. It's not a matter of cost since having the wheel shipped out, made 2 inches wider, shipped back, powder coated brings up the cost to almost double of what one new wheel would have been. But I'll tell you this; The look on people's faces (those who know slingshots and what the stock wheel looks like) is priceless when they see this big fat 345 tire on a stock appearing wheel. Even this past winter during Bike Week in Daytona, both Polaris people and a customizer of sports bikes were impressed to see that tire on a stock wheel. The small changes that yields huge results shouldn't be overlooked by the fact that there are other choices in wheels.





    :00000436::00000436::00000436:
    I also like the stock rims on my 17SL LE


    @funinthesun who did use to widen the rim? Also what spacer did you use?

    John
    2017 SL LE Midnight Cherry
    :COILOVERSS::TURBOSS::MOTOROILSS::FILTERSS::COLDAIRSS::DONKEYSS:

  • I must be the odd ball in the group since i really like the stock 2015 SL wheels. It's not a matter of cost since having the wheel shipped out, made 2 inches wider, shipped back, powder coated brings up the cost to almost double of what one new wheel would have been. But I'll tell you this; The look on people's faces (those who know slingshots and what the stock wheel looks like) is priceless when they see this big fat 345 tire on a stock appearing wheel. Even this past winter during Bike Week in Daytona, both Polaris people and a customizer of sports bikes were impressed to see that tire on a stock wheel. The small changes that yields huge results shouldn't be overlooked by the fact that there are other choices in wheels.





    Pretty cool! Didn't know you could do that...I like the older SL rims also and have 2 sets of them. Where did you send the rim, how much did it cost if you don't mind and how was the offset affected??thx

  • AFAIK, http://www.weldcraftwheels.com is the only national wheel widening company. There may be others, but these guys are usually considered the goto company for wheel mods.

    Correct, but Stickerdick has used another company to have his wheel done. Not usre of their name, but he's been happy with the results. As long as you get a wheel adapter that spaces the wheel back outward the same amount it came inward, you'll have the same offset as the stock wheel was.

  • Correct, but Stickerdick has used another company to have his wheel done. Not usre of their name, but he's been happy with the results. As long as you get a wheel adapter that spaces the wheel back outward the same amount it came inward, you'll have the same offset as the stock wheel was.

    Hopefully, he'll post the name.

  • After reading that @StickerDick had used a different company to widen his wheels, I Googled "Aluminum wheel widening" and I found these listings -


    Michigan - Welcome to Weldcraft Wheels | Weldcraft Wheels


    California - eric vaughn machine: aluminum wheel widening and narrowing


    Texas - RimSpec - Wheel Repair & Rim Repair Specialist Bent | Damaged | Curb Rash | Cracked | Powder Coating | Classic Wheel Restoration (also list a Miami phone number)


    I also found several sites that repair wheel damage, but none of them mentioned anything about widening.

  • I just emailed RimSpec (Texas) and requested cost info on widening my 18x9.5" rear wheel to 18x11". I assume I'll need a 3/4" spacer similar to this one - B07DWK6YM3. It uses 12x1.25 studs and has a 66.1 mm bore to match the stock wheel.


    Quick response (just over 1 hr) - $300-350 per wheel.


    I may just try this since it will cost (wheel mod + spacer) about the same as buying a single wheel while matching my stock front wheels. I want a wider 18" wheel so I can try an Achilles ATR Sport 2 305/30R18 tire at a cost of $102-150, but most sites currently have them out of stock. Catch 22 - Don't want to mod the wheel until I know the tire I want to try is available.


    After some searching, I found one at Onlinetires for $133 including shipping and road hazard coverage. Guess once I get the tire, I'll have the wheel modded.

    Edited once, last by BKL ().