Are 235/75/15's a suitable tyre for the SRX?

[Cabmaster]

Hi all

I just need some advice on tyres please.

My SRX came standard with the skinny 205/80/16 tyres. Great on tar and great on soft sand if you deflate to 0.5 bar! However, my personal opinion is that this size tyre is more suited to the commercial Hilux delivery vehicles and so I made a change.

So, I changed to a 15 inch Toyota mag rim with a 245/75/15 Goodyear Wrangler AT/SA.

According to my calculations and research, the new tyre is 1.9% larger in diameter than the original tyre (which I believe to be well within the manufacturers recommended range of 2.5 - 3% maximum when upsizing tyres).

As expected, I have noticed some loss in power and some change in gearing. I’m not sure how much of an effect the width has on rolling resistance. The change is probably more noticeable due to the fact that it is a 2.5 D4D and not a 3L. I’m not sure at this stage how it’s affecting fuel consumption.

At this stage, I do have the option of changing the tyre to a 235/75/15 (slightly more narrow than the 245, but exactly the same height as the original tyre). Gearing should therefore go back to normal. I assume power will be restored and fuel consumption better.

Basically my question is, should I rather change to the 235’s?

Some of the online tyre size calculators recommend the 235’s as the correct tyre to go for if upsizing from the 205/80/16.

At the moment, I enjoy the small, although noticeable lift of 7.5mm extra ground clearance.

Would appreciate some advice.

[Ou vale1]

I run on 265/65/17's, with 20mm front spacers, no problem.

[ChrisF]

Brett I have gone down this same road ....

I really wanted the 235 tires .... just could not get stock.

In the end I did the 245 install.

What caught me off gaurd - on the GPS the 245 runs at the SAME GPS speed as the 205 !! I know the maths says it should be 3% faster, but it is not ..... this is on BFG.



The tire bulges ever so slightly, and after 50 000 km you will note it wears more on the inside due to this bulging ...

[Cabmaster]

Hi Chris,

Thanks for the reply.

What rim size are you running the 245's on.

I can get stock of the 235/75R15 in the Dunlop Grandtrek AT3 from our local Dunlop dealer around the corner. I'm just wondering if it would be a better option for me.

Currently I am running 245/75/15 on 15 inch rims and the tyre look so much wider, bulkier and heavier than the guys that run 245/70/16 on the steel rims.

[ChrisF]

Brett I use the standard SRX steel rims - this the slight bulging.

[Cabmaster]

I run on 265/65/17's, with 20mm front spacers, no problem.

Hi Koos,

Are you running the 265/65/17 on your 2.5 SRX?
How do you find fuel consumption with these tyres?

[ChrisF]

I run on 265/65/17's, with 20mm front spacers, no problem.

Hi Koos,

Are you running the 265/65/17 on your 2.5 SRX?
How do you find fuel consumption with these tyres?

seems he has the new high power 2,5 ....

[Ou vale1]

With the chip not much has changed consumption wise, slightly better top-end, I can comfortably cruise at 140.

[ChrisF]

With the chip not much has changed consumption wise, slightly better top-end, I can comfortably cruise at 140.

with the camper canopy on mine I need a mine shaft to get to those speeds

[Cabmaster]

Hi Chris,

Are you running 245/70/16 or 245/75/16?