Swedish Mike Posted July 12, 2006 Report Share Posted July 12, 2006 but 235/30? why does Toyo say 8.5" only?I don´t know but a 8" rim and 235 mm tires match good, the profile is only about height./Mike Link to comment Share on other sites More sharing options...
CaughtLikeFire Posted July 12, 2006 Report Share Posted July 12, 2006 I don´t know but a 8" rim and 235 mm tires match good, the profile is only about height./MikeThe lower sidewalls require more rim width for proper support. With less sidewall, it's harder to "pinch" the two tire beads closer together on a narrower rim. So on a really low profile tire like 235/30/18, your rim width needs to match the distance between the inner and outer tire beads when the tire is not mounted - you basically have too litte sidewall to angle the bead inwards to safely mount the tire on a rim narrower than 8.5" 235 does work well in general on an 8" rim. We can see this on the OEM S60/V70R tires with a 40 aspect ratio. When we start to remove sidewall, it gets tougher to safely pinch the tire inward to mount on the rim. by the time you get down to a 235/30/18, the tire bead virtually needs to be flush with the edge of the rim. Link to comment Share on other sites More sharing options...
Swedish Mike Posted July 12, 2006 Report Share Posted July 12, 2006 The lower sidewalls require more rim width for proper support. With less sidewall, it's harder to "pinch" the two tire beads closer together on a narrower rim. So on a really low profile tire like 235/30/18, your rim width needs to match the distance between the inner and outer tire beads when the tire is not mounted - you basically have too litte sidewall to angle the bead inwards to safely mount the tire on a rim narrower than 8.5" 235 does work well in general on an 8" rim. We can see this on the OEM S60/V70R tires with a 40 aspect ratio. When we start to remove sidewall, it gets tougher to safely pinch the tire inward to mount on the rim. by the time you get down to a 235/30/18, the tire bead virtually needs to be flush with the edge of the rim.We normally use 225/35-18 on those rims when we mount them on 850, can´t see why 235/30 shouldn´t fit.Call me stupid but a 235 mm tire will have pretty much the same mounting width on all profiles, that´s the point!/Mike Link to comment Share on other sites More sharing options...
CaughtLikeFire Posted July 13, 2006 Report Share Posted July 13, 2006 We normally use 225/35-18 on those rims when we mount them on 850, can´t see why 235/30 shouldn´t fit.Call me stupid but a 235 mm tire will have pretty much the same mounting width on all profiles, that´s the point!/Mikeyou're not stupid at all the 235's physically fit, I'm sure - that's what you're saying and I agree.I was just explaining why the manufacturers don't "approve" an 8" rim width for 235/30/18.The sidewalls on most tires mounted on an approved rim width will look like this: \ / They angle inward.As the sidewall gets shorter, you have less material to bend/flex and can't get the same angle or can't mount it as easily/safely. A 235/30/18 will have very little sidewall to bend/flex so the sidewalls will need to meet the rim almost straight down like this: l l It doesn't mean you can't make them go like \ / to fit on an 8" rim, but the 8.5" width will result in a shallower sidewall angle and put less strain on the sidewalls. Thus it's easier to mount properly and possibly a little bit safer to drive on an 8.5."Also keep in mind that you will get a larger contact patch running a tire closer to its maximum rim width than its minimum. With the same tire, running a 235/30/18 on an 8.0 rim may not give you a true 10mm extra treadwidth over a 225/35/18 on an 8" rim since you're pinching the sidewalls more to make it fit. So you have to decide if the 235 is really worth it. Link to comment Share on other sites More sharing options...
steve s Posted July 13, 2006 Report Share Posted July 13, 2006 Right now I am running 225-40-18 and get some bad rubs on my 18x8 wheels.why aren't u running 225-35-18 if u wanna try to remove rubbing? Link to comment Share on other sites More sharing options...
Über855R Posted July 13, 2006 Author Report Share Posted July 13, 2006 why aren't u running 225-35-18 if u wanna try to remove rubbing?Well that will be the next step. If I run 18x7.5 with 225-35 I am hoping for no rubs and if that doesn't work I guess I will try 215-40 but I am kind of hoping with the 225-35 and the tpms I wont have any problems with rubs or low air pressure in such a low sidewall tire. This is getting off topic but I guess its still close. The wheels are going to be 18x7.5 +43 iforged black center 3 piece evolution. I can't wait!!!! :D Link to comment Share on other sites More sharing options...
Swedish Mike Posted July 13, 2006 Report Share Posted July 13, 2006 Well that will be the next step. If I run 18x7.5 with 225-35 I am hoping for no rubs and if that doesn't work I guess I will try 215-40 but I am kind of hoping with the 225-35 and the tpms I wont have any problems with rubs or low air pressure in such a low sidewall tire. This is getting off topic but I guess its still close. The wheels are going to be 18x7.5 +43 iforged black center 3 piece evolution. I can't wait!!!! My old MasItaly Manager was 18x7.5" and I ran Pirelli 215/35-18 for a start, worked but the rims got blasted and needed new paint in 6 months.Sold the tires and mounted Falken 451 225/35-18 and these were perfect, covered all rim facing the road and looked really good, better grip was a bonus. /MikeEdit: Here´s some pics with the 215´s. http://volvospeed.com/vs_forum/My-First-85...000-t52719.html Link to comment Share on other sites More sharing options...
Über855R Posted July 13, 2006 Author Report Share Posted July 13, 2006 Well I guess its 225-35's ftw, Nice pics by the way Link to comment Share on other sites More sharing options...
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