Gummybears

just wondering why the tread width on the ET Street R is so much less compared to the r888? isnt more tread width = more traction? just at loss why didnt MT make this tire tread width any wider? or is there just some kind of secret.... 7.8 is smaller then any other tire at 225/50/15 and this tire is a drag tire. would not more be better?

for drag purposes anyways


r888 225/50/15
section width 9.1" tread width 8.7"

vs

MT et street R 225/50/15
section width 9.1" tread width 7.8"

Ghettochild2600

Most people will tell you that tread width or wider tires equals more grip which is incorrect. The primary limiting factor is the coefficient of friction, or simply put, the tire compound. PSI is a huge factor too for the contact patch. That said these tires have different compounds. The r888 is focused more towards race/drag performance where the MT street R is focused towards street/race. With them being made of different compounds the MT Street R can probably get away with the smaller tread width while maintaining street performance. As far as a drag tire in that size the BFG g-Force T/A Radial Drag Tire as well as the r888 are both superior. However, If you're just doing drag then a smaller wheel diameter and a taller/wider tire for a thicker sidewall will give you more bite.

Gummybears

Hmmm forgot psi has a lot to do with contact. Thanks!

Does this makes since, since r888 is meant to run with higher psi say 40psi, then I decide to lower to15psi, since the tread width already being so wide, would the center of the tire bow inwards?

Whereas the Mt street R is less tread width meaning the tire being more rounded, once on low psi 15 or so it'll be much more contact patch/treadwidth or more flat then the stated info? And it won't bow out in the center?

If this makes sense.... does it sound right?

Ghettochild2600

Makes sense and It shouldn't bow inwards. If anything it should bow outwards while the tire rotates due to centrifugal force. Since the patch that touches the road is directly related to tire pressure and the weight on the wheel you can calculate the size on the patch by dividing the weight on the tire by the tire pressure. For example a 850lb load on your driver's side tire at 33psi has a tire patch of 25.75 square inches. The shape of that patch will vary depending on the width of the tire, but regardless of the tire you fit, that's the patch of rubber that will be touching the ground. Extremely stiff low profile tires will deviate from this a bit and actually give the affect of having more tire pressure. that said I would advise against using anything less than a 40 or so section tire height.


So in short when you fit a wider or more narrow tire, what ultimately changes is the shape of the contact patch. The patch gets wider horizontally and shorter on the vertical direction

Gummybears

hmm sounds a bit complicated to calculate but thanks for the info help cleared a lot of my questions i could not find =X