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View Full Version : Biggest tire on 17x7.5, and general tire size questions

TheJuggernaut
07-15-2009, 09:10 AM
Hi everyone,

I'm currently running 235/40/17 RT615s on my E30, on 17x7.5 Kosei K1. They fit perfectly. I'd like to switch to R888s but the toyo site says they are only approved for an 8-9.5" rim. Can anyone tell me for a fact whether or not the 235/40/17 R888s will fit a 7.5" rim without problems (like sidewall buckle... I REALLY doubt it but I've never owned a set of these).

I actually even considered trying 245/40/17s and that leads me into a follow up question. Can you guys give me your opinions on stuffing overfat tires on? I've heard opposing schools of thought on this. Some guys run 235s on 9.5" rims, others stuff the biggest that will fit - for instance, in the GRM R-comp comparo a few months ago, they were stuffing 285s onto an 8" rim. They had to back off the size on the V710 because the sidewall buckled.

I can think of logical arguments for and against either side, but what I'd really like to hear is guys who have actually tried/are doing this, and whether or not they found it to be good and why/why not.

Thanks a lot,
Dmitry
billyekracer
07-15-2009, 11:34 AM
I have read that the ideal wheel width would be at least as wide as the contact patch of the tire...235 tires are 9.2" wide and no larger than 10% wider than the contact patch. I'm sure these are guidelines based on tire constuction...but for the Toyo's I believe they are accurate.

I have also been told (by Toyo) that within their recommended wheel widths...you should, whenever possible use the largest size recommended.

They know what each individual tire needs to be used to its full potential.

By squeezing a tire onto an inappropriately sized wheel, you are taking away the full benefit of sidewall construction and contact patch...all you are gaining is the extra weight of the larger tire.

That is what I believe :D
G-ForceJunkie
07-15-2009, 12:54 PM
For what it's worth...I've run a 245/45-16 RA-1 on a 16x7 wheel. It's not ideal, but it works.
Trackside
07-15-2009, 04:28 PM
Contact region sponsor and competitor

Jeff
Toronto Tirecraft
905-760-1130

I am sure he will give you the correct information. Very knowledgeable and friendly
TheJuggernaut
07-15-2009, 04:34 PM
Thanks for the input guys, keep it coming.

Contact region sponsor and competitor

Jeff
Toronto Tirecraft
905-760-1130

I am sure he will give you the correct information. Very knowledgeable and friendly

I'm not sure if I spoke to Jeff but I've called Tirecraft with this question and I was just quoted the Toyo approved range (8-9.5).
jeffrey
07-15-2009, 04:39 PM
The R888 seems to wear quickly in the centre. I therefore believe that it would be best to stretch the tire as much as possible. The R888 also has a larger than average casing constuction

Jeff
Torontotirecraft
TheJuggernaut
07-15-2009, 04:44 PM
The R888 seems to wear quickly in the centre. I therefore believe that it would be best to stretch the tire as much as possible. The R888 also has a larger than average casing constuction

Jeff
Torontotirecraft

Thanks Jeff! What size would you personally run on an E30 with 17x7.5?
jeffrey
07-15-2009, 05:21 PM
235/40R17 RA1 or 225/45R17 R888. They are both the same side bye side. Both in stock too!

Jeff
TheJuggernaut
07-15-2009, 05:23 PM
235/40R17 RA1 or 225/45R17 R888. They are both the same side bye side. Both in stock too!

Jeff

REALLY!? Would you happen to have 4 235/40/17 RA1s in stock...? :D
jeffrey
07-15-2009, 05:28 PM
I do! And being in the tire biz, I'd be pleased to sell them to you.

Jeff